2.2.1 Magnetic–Dielectric synergy

The megnatic and dielectric synergetic effects are critical factors and components for EMI shielding and microwave absopriton. The comboniation of dielectric as well as magnetic attributes of the developed composite could be attained by the impedance matching. The reduction in surface reflection of electromegnatic wave absorption with strong attenuation capacity of an incident waves which contributes an excellent absorption effectiveness (Saini and Aror, 2012). The study can be made on impedance matching; and calculated through Eq. (13) and Eq. (14).

Impedance Matching: The EMI shielding and microwave absorption can be indicated through “μ_r “value to the “ε_r” the values for the higher reflection loss (R_L) response. Therefore, the complementary example lies between dielectric and magnetic loss; which has been previously reported, showing that, the moderate EM parameters of Carbon and nickle C–Ni composites resulted as Z value over a wide range of bandwidth. The results are corresponds to a broadband EMI and MA absorption. It has been revealed that enhanced EM wave absorption of Co/ZnO/C based composites was attained by the metal–organic framework (MOF) primarily beneficial and satisfactory balance between the dielectric and magnetic attributes of each component as counter part of the composite (Saini and Aror, 2012). The second and foremost common factor is attenuation capacity of the composites for betterment of the shielding performance amongst the megnatic and dielectric loss as synergistic effect.

Attenuation Capacity: The property is measured by using the Eqnation the attenuation capability of a magnetic–dielectric based composite shows a stronger effect than the dielectric and magnetic constituents. However, a crictial component among the core and shell composites is excessively higher with dielectric loss. Despite of that, the developed nanocomposite showed a reaseonable attenuation capability and their impedance matching can barely studied, leading to a narrow EAB. Wheareas, according to the design of EM wave absorbent materials in the nanocomposite assembly certainly requires rational dielectric retention to accomplish the reasonable steadiness and stability between the frequency dispersion (Fd) properties of dielectric and magnetic spectra. Furthermore, several new strategies has been practiced and used for enhancing the magnetic loss tangent; whereas, improvements made in the dielectric attributes to the metal organic framework, which are remarkably anticipated for the better impedance matching (Saini and Aror, 2012). Within microwave frequency bands, dielectric polarization includes both interfacial and dipolar mechanisms. The dielectric properties are based on polarizaiton and conduction attributes. Within a microwave frequncey bands are related to dielectric polarization which comprising the interfacial, dipolar, and defects induced poliarzation mechanism. However, the polariztation is rasised with interfactial charge, when heterostructured assemblies consisting of dielectric attributes with reorgenizaiton of the dipoles. However, the conduction loss in low-dimensional materials are responsible for the transport mechanism with more conductive paths and the electron hopping effect as defects induced barriers, and can be determined from the increase or decrease of the filler contents and carrier mobility.

Additionally, the dipolar polarizaiton and dielectric mechanisms are correlated to the several induced defects on the surface of low dimensional materials and which is quite interesting where as the fuctional groups works as work function due to the presence of these reactive species on the suface of two dimensional materials may improve interfacial bonding between two different counterparts. However, on the otherside, the large specific surface area may also assists in the enhancement of polirazation of electromengnatic wave with exceptional electrical conductivity in low dimensional and two dimensional materials. Therfore, due to excellent conductivity the 2D materials, such as graphene and MXene, can introduce a great impact on the dielectric attributes and the conduction loss. The geometrical shapes could aslo infleuce these polarizaiton effects, such as in 1D materials with higher anisotropy aspect ratio, chirality, and plasma resonance reuilting in multiple scattering. However, the polarizaiton is greatly influence by the propagation behavior of the incident EM waves, which leads to an additional EM energy loss. Keeping in view these factors in consideration the 2D materials showed an exceptional behavior which resulted as increased demand and potential use of dielectric materials in the field of EM shielding and microwaves absorption (Saini and Aror, 2012).

2.2.2 Magnetic loss

The megnatic loss in the 2D, and 3D nanocomposites structures are totally dependent and based on the size confinement. Wheras, the frequency dispersion includes, the complex permeability in the low dimensional materials containing the magnetic attributes. The properties are generally characterized by four main mechanisms: domain-wall motion, natural resonance, exchange resonance, and eddy current. In which, the magnetic domains are bsed on geometrical and morphological arrangement, size, shape, crystal size, crystal, structure and growth; which work as external magnetic field. Wheras, the higher electrical conductivity of such low dimensional MOF and metal complexes containg magnetic characteristics could enables the cohort of eddy currents and can potentially reduce the magnetic loss capacity. The such contrivancies among the 2D and low dimentional materials demonstrates that the low dimensional materials in terms of surface morphology, size, and crystalline nature could greatly be used to fine tune the magnetic loss capacity. Subsequently, the optimistic impedance matching and attenuation capacity are are also considered as key factors for improved MA and EMI shielding effectiveness (Saini and Aror, 2012).

2.2.3 Dielectric loss

Furthermore, to clarify the mechanism, the electromagnetic parameters including the real (ε′ and µ′) and imaginary parts (ε″ and µ″); wherein ε′ and µ′ represent the storage capability of electric and magnetic energies, respectively. However, the values “ε″ and µ″ denote the dissipation capability of electric and magnetic energies, respectively. Generally, the dielectric loss of the aerogels materials is attributed to polarization relaxation and conduction losses (ε_p″ and i″, respectively), because of the uniform incorporation of a ferromagnetic component from the dielectric rGO aerogels. The negative μ″ value indicates that the magnetic energy from the induced magnetic field of the materials is transformed into the electric energy (Saini and Aror, 2012).

Generally, the magnetic loss is attributed to the eddy current and magnetic resonance loss (natural and exchange resonance). The eddy current loss is evaluated using Eq. (16) and Eq. (17).

Whereas;“μ₀” denotes the vacuum permeability; “C₀” is positively correlated with “d²” and “σ” (conductivity). The “C₀” value is almost stable in the range of 14–18 GHz in the C₀ − f curves, indicating a magnetic loss from the eddy current loss. In contrast, magnetic loss will be generated from natural resonance loss.

While; the eddy current loss is the dominant factor at frequencies of 9–18 GHz. Therefore, a good impedance matching means that more incident microwaves penetrate into the materials rather than being reflected, thus guaranteeing ultra-efficient MA properties. The impedance matching characteristic can be described as the Eq. (18) and Eq. (19) (Saini and Aror, 2012).

Where Z_in represents normalized input impedance of the absorbers, Z₀ refers the free space impedance, f, d, c, μ_r, and ε_r are the frequency, thickness, velocity of electromagnetic waves in free space, complex permeability, and complex permittivity of the absorber, respectively. The attenuation constant “α” is another vital factor for excellent MA performance and reflects synergetic dielectric and magnetic loss capacity. The value of α can be expressed as the following Eq. (20).

Where “f “and “c” are the frequency and electromagnetic waves in free space, respectively. The “α” values is increased by increasing the frequency levels. Noticeably, the “α” values of the composites films are much higher than those of pristine films in the entire frequency range, demonstrating their stronger dissipation capacity to electromagnetic waves. The higher “α” values are attributed to enhancement of dielectric loss and magnetic loss in composites. Among them, the dielectric loss plays an important role for increasing attenuation ability of the developed composites. It should be pointed that the high α values and excellent Z are mutually exclusive and difficult to obtain simultaneously for single carbon-based materials (Saini and Aror, 2012).

2.3.1 Uniform layered structure

The layered structure favors multiple reflected and scattered waves among contiguous sheets due to the absorption caused by reflection, conduction and interface/dipole polarization loss at the material surface, and the resulting composite films have excellent performance at 8.2–12.4 GHz demonstrating the high EMI-SE of 37.1 dB over the frequency range of 8.0-18.0 demonstrated in Fig. 3 (b) (Liu, 2021). Additional the EMI shielding ability is sound preservation in extreme situations for example high temperature, acid/salt based solution, with long-term sturdiness. In addition, the parameters are generally based on its stable and excellent electrical conductivity, & exhibits fast, stable joule heating performance, which shows that, the higher thermal stability and deicing effect are required under practical working conditions (Liu, 2021).

2.3.2 Segregated structure

The designing of layered structures for electromagnetic and shielding materials is easier and highly flexible assemblies as compared to segregated and foam structures. Therefore, the use of developed such multiple to few layered structures on flexible, sheets films of polymeric materials and fibrous materials is highly anticipated for shielding against the different wearable electronic devices. These 2D material based composite assemblies have unique properties and suitable for shielding effectiveness due to their multiple layers as a dual functionality, in which each layer works its own real time functionality, for example reflection, absorption, conductivity, and EMI shielding performance as demonstrate in Fig. 3 (c). The absorption and reflection loss are key factors being considered as dual nature of the materials toward an improved or reduced electrical, and thermal conductivity; which results an enhanced SE value. The shielding materials with different assemblies varying shape and size from 0D to 3D,  theses structure shows great impact on EMI shielding performance, the structural shapes are demonstrated in Fig. 3 (c), reflection and transmission of an incident waves; which is caused by the conduction and reflection loss mechanism between different layers of the segregated nanocomposite structures (Liu, 2021).

2.3.3 Foam structure

Likewise, the segregated structural arrangements, the establishment of highly conductive porous assemblies are needed to be designed from various 2D materials, with hetero-genous structures when mixed together with polymers, conductive polymers and metal organic frameworks. In, such assemblies, the polymer loaded with different content percent of 2D materials and MOF work as filler in the form of multidimensional gradients ranging to 0D, 1D, 2D and 3D in a foam structure as demonstrated in Fig. 3 (c). The properties of each nanocomposite in the assembly can be fine tuned and optimized by variation in parameters for example, shape, size and conductive paths, with variable loading of fillers as demonstrated in Fig. 3 (c). However, higher electrical conductivity is attained by varying the filler content percent , to reduce or overcome the limitation of the forces of interaction between conductive polymers and filler (Liu, 2021). The composition of different nanocomposite and polymer matrix with varaible filler content percent is demonstrated in Table 1.

The required parameter are achievd by dispersion of CNT and other fillers which comprise several available reactive cites. Secondly, the higher conductive paths are introudced with strong adhesion and interfacial bonding; which is due to the presence of reactive functional groups on the surface of GO and the “π-π” conjugation between polymer and carbon based materials as filler. The desinged syntactic foam structure showed an average EMI sheilding efficiency (SE) of 28.2 dB, with a density of 0.02 g cm⁻³. Whereas, in the developed multilayered assembly each individaul porous unit cell has a higher interfacial interaction between eachother, resulting as strong mechanical compressibability and higher absorption of EM waves at available cavities as well as the deflection of the incident waves as presented in Fig. 4 (a-e) respectively (Liu, 2010).

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Fig. 4

Shielding mechanism of bimetallic polymer based 3D porous structure (a), SEM images of segregated structure of nanocomposite porous films (b), shielding performance of developed nanoarrays of 3D carbon foam (c-e). The image is reproduced with permission to copyright materials Wiley Online, 2020 reproduced with permission to copyright materials Elsevier, 2022 (Wei et al., 2022).

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In present work proposed for the microwave frequency 2–18 GHz x-band, to overcome such broader challenge, a high-efficient material has been reported so far and the absorption mechanism was attained over a band of (greater than 7 GHz). The size dependency of the composite exhibited an improved microwave absorption with a thickness (<3 mm). The proposed work demonstrates a new strategy to accomplish lightweight and highly efficient microwave absorption materials in the form of porous foam structures. The three-dimensional (3D) carbon foam (BNA/3dCF) was prepared from carbon loaded cobalt in organic solvent and water by using simple hydrothermal technique (Wei, 2022). A hollow carbonous spheres were made from Nb₂O₅@SHCs with unique attributes and morphological structure. The Nb₂O₅@SHCs with rambutan-like morphology were synthesized using a simple hydrothermal method. The electromagnetic wave absorption performance of Nb₂O₅@SHCs was significantly improved due to high reflection losses (R_L) and effective absorption bandwidths (EAB, R_L <  − 10 dB). The minimum reflection loss (R_Lmin) of a 3.25 mm substrate is 52 dB, while the maximum EAB of a 2.8 5 mm substrate is 5.28 GHz. Multiple reflections and scattering were increased in Nb₂O₅@SHCs as their interface polarization is enhanced, and their impedance matching was also improved, which increased their EMW absorption capacity. Rambutan-like Nb₂O₅@SHCs nanoarrays showed a great potential toward the absorption of high-performance electromagnetic radiation (Chen et al., 2022; Yu et al., 2021).

Carbon foam, a novel and new type of material for microwave absorbing is capable to greatly retain the electromagnetic wave by using melamine based highly efficient porous micro-structure foam as a template. The designed porous structure showed significant improvements due to the high electrical and thermal conductivity of micro cavities to restrain the wave propagation and currents. As a result a large number of waves has been scattered with more number of available sites towards improved electromagnetic absorption through conduction and conviction (Zheng, 2022). More interestingly, the shielding performance is attributed towards greater sustainability and protection from the electromagnetic waves by carbon layers without affecting the structural assembly; which is attributed to low oxidation of MOF. So that, the composite had capability to retain the dielectric properties of carbon foam with an exceptional SE and an excellent magnetic behavior and higher impedance matching as well as magnetic loss attributes (Sankaran et al., 2018).

3.1.1 Graphene-CNT/polymer-based composites

The multi-walled carbon nanotubes (MWCNT) with reinforced polypropylene (PP) nanocomposites was prepared by melt processing technology through a twin-screw extruder. Compared with the sample without filler (PCN), the tensile strength of the nanocomposite is increased by 27 %. The introduction of MWCNT increases the conductivity from 2.07 × 10^-10 to 4.21 × 10^-6 S/cm (Wang et al., 2021; Lai et al., 2020; Xie, 2021). The frequency range of X band (8.2–12.4 GHz) was measured with a vector network analyzed; when aqueous solution of GO was loaded at 5.0–10.0 wt% of the CNT showed significant improvements in electrical conductivity as well as microwave and EMI shielding effectiveness as compared to pristine rGO films a loaded with Fe₃O₄ nanoparticles showed an incident waves reflected from the surface of graphene films and ferric oxide nanoparticles for EMI shielding performance with higher reflection as demonstrated in Fig. 13 (a). Similarly; in another work presented on 2D materials MXene was for microwave and EMI shielding. The MXene films were decorated with Fe+ and were processed via solvothermal approach, The Fig. 13 (b) demonstrate the compact MXene sheets towards improved EMI shielding with magnetic loss, conductive loss, dipolar polarization and interfacial polarization of the MXene sheets after widening of MXene stacked layers for enhanced EMI shielding (Wang et al., 2021; Lai et al., 2020; Xie, 2021). However, the high performance materials for better EMI shielding effectiveness (EMI) with improved shielding efficiency (SE) is achieved with enhanced electrical and thermal properties due to the increasing the conductive fillers, which results as a high stiffness and increased compressibility of the composite foam structures (Li, 2021).

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Fig. 13

(a) Development of GO & Fe₃O₄ based composites reproduced with permission of copyright material Elsevier; 2018 (Yang et al., 2018), (b) MXene and Fe₃O₄ composites, reproduced with copyright permission by Elsevier; 2019 (Zhang et al., 2019), (c) self healing carbon nanotubes/arylic polymer composites. This figure has been reproduced with the copyright materials by Elsevier (2021) (Zhan et al., 2021); and (d) ultra light and ultra thin carbon nanotube/polyimide foam and graphene nanocomposites for microwave absorption. Reproduced with permission of copyright material Elsevier; 2021 (Wang et al., 2021).

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In which, the agglomerations results an enhanced polymer to filler interaction with stronger bonding forces between conductive filler and PI polymer matrix as demonstrated in Fig. 13 (b). Another, study made on carbon nano tubes CNT dispersion was achieved in the polymer matrix, due to the chemical surface functionalization of reactive sites as chemical groups on graphene oxide (GO) films, which resulted as improved “π-π” conjugated bonds between GO films and CNT as demonstrated in Fig. 13 (c). The developed nanocomposite foam demonstrated an average EMI performance of 28.2 dB and specific (SSE) of 70–50 dB cm² g⁻¹ with very little density of 0.02 g cm⁻³. For the time being, the multiple layered structures developed on graphene films and showed strong chemical bonding between PI matrix and graphene films (Yang, 2018; Zhang, 2019). The designed composite foam structure showed a better cycling loading and unloading during the compression stability analysis. These topographies endorse the probable use of the CNT/graphene/PI foam as lightweight, compressive, heat-resistant toward an improved EMI shielding and electromagnetic wave absorption as demonstrated in Fig. 13 (d). The maximum EMI shielding effect of − 21.07 dB was attained, which is effective value for EMI shielding. The results also demonstrate, that \as prepared nanocomposite material is highly effective and suitable for EMI shielding to meet the requirements of the industry. The newly developed a lightweight, highly flexible, conductive and efficient EMI shielding (Wang et al., 2020). Similarly, the graphene loaded with silver (Ag)/and other metallic nanoparticles, instead of magnetic carbon nanotube (mCNT) composite loaded on polypropylene (PP) fabrics by a facile spray deposition technique (Yang, 2013) The nonwoven PP fibers coated with MCNTs after plasma modifications and Polydopamine (PDA) assists in the development of hydrogen bonds between Fe₃O₄ on polymer surface towards an improved adhesion propertie as compared to untreated nonwoven pp fibers. The introduction of mCNTs significantly improved the electrical conductivity and EMI shielding performance of the Ag/mCNTs composite coating was nearly about to 8.2–12.4 GHz (Zhan, 2021). Thus, the Ag/mCNTs composite coating exhibits excellent EMI shielding effectiveness (SE) of 61.1 dB and a specific SE (SSE/t) of 2811.78 dB cm ² /g, and revels a good stability, maintained over 91.6 %,80.2 % and 69.8 % enhanced EMI SE after washing tests. Therefore, Ag/mCNTs-coated PP fabrics can be a reliable candidate for exploring flexible electronics for high-performance EMI shielding fabrics and porous assemblies with better stability (Liang, 2020; Bai, 2022). Another work based on silica carbide (SiC) loaded with graphene also showed improved SE performance over different thicknesses (∼10, and ∼ 15 nm) and developed by using freeze drying method. The effect of SiC shell and nanoparticles with variable size and thickness greatly influence on the overall MA and EMI shielding properties of the resulting GO-polymer nanocomposite. The as coated SiC shell effectively promotes the dispersion of CNTs in the geopolymer matrix due to the chemical reaction between SiC and polymer composites as presented in Fig. 14 (a & b) (Li, 2022).

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Fig. 14

Development of GO and SiC slurry into as a directional free standing porous films (a) orientation of as prepared foams/aerogels, (b) GO and rGO with SiC aerogels, (c) developed aerogels with freeze drying and thermal annealing, and (d) Microwave reflection loss (R_L) response of aerogels, reproduced with permission of copyright material, Elsevier 2018 (Jiang et al., 2018).

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In another work, made on the development and designing of a lightweight spongy structure looks a like bone-like made of graphene@silicon carbide (SiC). These aerogels were fabricated by the simple available method i.e freeze-casting of GO coated SiC whiskers made from the slurry through thermal reduction of GO@SiC to produce highly flexible and porous aerogels (Jiang et al., 2018). The developed sponge like structure showed exclusive hierarchical assembly with well oriented and good ordered structure of graphene@SiC. These aerogels were formed by graphene wrapped SiC whiskers, which hold pronounced benefits for example, having a low density (72 mg/cm³) with a higher MA performance.The developed assembly showed a minimum reflection loss and attained EMI performance of − 47.3 dB at 10.52 GHz for a very smaller thickness of 3 mm. The effective bandwidth of reflection loss was reached to ≤  − 10 dB for 4.7 GHz. These out performance, demonstrates that the developed composite is a novel graphene@SiC aerogels and highly efficient material for high-performance microwave absorption application. The dispersive core and shell of the altered CNTs can be more improved by growing the thickness of SiC. However, the insulating SiC shell may restrain or hindered delocalization of electrons and reduced when the SiO₂ shell is thin; the conduction of CNTs was disintegrated. The electrical properties are also recovered during the polymerization process, which may attribute to the higher interfacial bonding and more interaction on molecular level (Jiang et al., 2018). A high EMI shielding efficiency (SE) of 24.2 dB is achieved for the geopolymer nanocomposite containing 5 vol% S-CNT and thin SiC shell as demonstrated in Fig. 14 (c & d). The ​​obtained values are more competitive than reported composites; when sample thickness and filler content are taken into account. To address the overheating and EMI problems of integrated electronic device is more important and essential towards the design of multifunctional materials with enhances EMI shielding effect (Chen, 2021).

In this concern, the anisotropic graphene and MWCNT were used to develop a continuous 3D continuous networks via KOH-induced hydrothermal and chemical reaction. Subsequently the graphitization was attained at 2800 °C, where the ratio of GO: mWCNT was kept 1:3, which is favorable for electrical and heat transport. The optimal thermal conductivity of the composite can reach 1.30 W m⁻¹ K⁻¹ at a low load of 2.77 wt%, which is 465 % higher than that of pure silicone rubber (0.23 W m⁻¹ K⁻¹) (Chen, 2021; Fu, 2020). However, the developed composite revelations a higher electrical conductivity with EMI shielding of −42 dB in K-band. Also, it still retains the flexibility of the matrix. This work provides the better understanding of lightweight functional materials for potential end use of microwave and EMI shielding as presented in Fig. 15 (a & b). The work reported on graphene/epoxy nanocomposites and aerogels with highly conductive polymer; i.e polyaniline nano structured (NWs) has been developed in the paraffin matrix. The loading percent of the graphene with CNT was varied to produce segregated composite films produced on simple filtration technique, on PET, and PVDF filter papers.Simillary some other works are also been reviewed in previous studies with continuously increased EMIS SE performance with variable size, thickness and filler content percent with and epoxy resins as presented in Fig. 15 (c & d) (Chen, 2021; Liao, 2022).

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Fig. 15

CNT-graphene oxide (GO) based porous aerogel converted into rGO-CNT based 3D structures of nanocomposites via sequential hydrothermal reduction (a), rGO-CNT decorated graphene films; conductivity (b), and EMI shielding effect (c), and computerized simulated image for rGO based layered assembly loaded CNT (d). Reproduced with copyright permission by Elsevier 2020 (Fu et al., 2020).

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Similarly, another Inspired work presented by successful manufacture of porous structure amongst the graphene filmstrip and the other 2D structures of MXene Ti₃C₂Tx as porous hetro structure made for superior performance towards EMI shielding. The composite films were prepared by using ion-induced and vacuum filtration of MXene and rGO porous composites for enriched microwave and EMI shielding. The developed porous structure of Ti₃C₂T_x/rGO films prevailing a compact surface and highly porous assembly inside. The resultant assembly showed higher electrical conductivity in which the mass fraction of GO and Ti₃C₂T_x was varied from 2:2. The maximum EMI shielding efficiency (SE) composite assembly including the rGO and MXene films extended up to (59 dB), and obtained a specific SE (SSE/t) of 37619 dB cm² g⁻¹ which is almost high performance achieved with similar materials as reported in previous studies (Huang et al., 2021; Duan, 2022).

Whereas, the resultant composite were also find to be highly water repellent and flame proof ability of rGO and MXene as compared to barely used materials. The synergistic effect is attributed to MXene and rGO films with similar behavior before reduction as (GO) and MXene are composed of similar chemical nature i.e hydrophilic behavior; which is due to the reduction of GO into rGO via elimination of oxygenated reactive functional (OH) groups from the surface of GO (Zhang, 2021; Cai et al., 2021). The attributes, are highly beneficent for resultant admixture and development of such composites for EMI shielding and other broader range of applications (Yan, 2018). The newly developed Ti₃C₂T_x/rGO porous assembly in the form of composite films generosities longer lasting thermal stability, improved electrical conductivity (σ) & EMI shielding performance (SE) (Yan, 2018; Cui, 2022). The environmental steadiness was greatly improved, which indicates a pronounced and probable use in various fields as ultra-thin, light and highly flexible EMI (SE also development of highly flexible instruments as presented in Fig. 16 (a & b).

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Fig. 16

EMI shielding performance of Graphene films loaded with MXenes films (a), SEM Images of segregated multiple layers (b), and EMI shielding design with simulated image of rGO and simulated image of MXene films (c). Reproduced with copyright permission by Elsevier 2021 (Zhang et al., 2021).

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Hence, the use of different 2D nano-materials in the form of 3D aerogels, hydrogels and porous hybrids is an alternative and effective method being used to fabricate the high-performance MA materials. The developed hetero structure in the matrix of the composite has higher interfaces and propels the magnetic loss mechanisms to overcome the problems of the 2D material by attenuating the electromagnetic energy as presented in Fig. 16 (c) (Duan, 2022; Zhang, et al., 2021).

However, the performance and reflection loss of − 20 dB of such nanocomposites is ranging from 7.0 to 17.5 GHz by refining the Debye relaxation. The graphene and epoxy resin demonstrates the replication loss of −14.5 dB over a frequency of 18.9 GHz; which may attribute to the change in multiple poles for the polarization of interfaces inside the nanocomposite material (Lan, 2022; Zeng, 2022). The production of GO based assembly of hybrid lamellar membranes has been developed with controllable layered structures to accomplish high performance microwave and EMI (SE). The interlayer spacing of the GO films in the membranes is controlled by using TiO₂ interpolate by different sizes and shape, while the stability of rGO membranes is improved by compressing with Polyethylenimine (PEI); as presented in Fig. 17 (a & b) (Saini and Aror, 2012; Lan, 2022; Liu et al., 2021; Luo, 2021).

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Fig. 17

Scaleable synthesis and fabrication of carbon coated MXene over PI composite (a), MXene films coated via air dyring approach (b), Carbon and MXene/PI composiste foam(c), Carbon and MXenes with reactive functional groups present on the modified surface mixed with PMDI (d), MXenes and PI coated fabric surface before (e), and after rolling and stretching of fabric (f). Reproduced with copyright material Springer 2022 (Zeng et al., 2022).

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The graphene and other 2D materials have such attributes as compared with traditional metal-based materials against the shielding effectiveness. Therefore, due to the limited use of metal complexes; which can only be reduced by using various conductive polymers, and their nanocomposites with different two-dimensional materials; and are considered as high flexibility, light weight, low cost and corrosion resistance due to the water and mist Fig. 17 (c-f) (Lan, 2022; Zhang, 2019). Though, the existing problems are still under investigation and considered as it become a global challenge; and being studied towards further improvements in the synthesis, fabrication and development of (electromagnetic/dielectric) materials composites. The developed nanomaterials and meta materials could effectively work under a versatile range of microwave and electromagnetic shielding with satisfactory shielding performance (Xu, 2021). Since, CNT and graphene with PDMS/PI as 2D material foams, fibers and aerogels are typically much more efficient to absorb in-plane than out-of-plane polarized waves. Keeping the polarized light and wave’s in-plane in 2D material foams as a critical factor other than coupling for the enhancement of MA (Zhang, 2022). The systems are integrated with variable architecture and structural assemblies’ i.e foam, fibers, modified with dopamine and poly dopamine (PDA) as shown in Table 3.

3.1.2 Graphene/metal-non-metal polymer-based composites

Metal-organic framework (MOF) during the construction of this item, the method of layering carbon fiber (CF) on the surface is a MOF. MOF loaded on the surface of the rice fragmentary structure homogeneous structure. MOF opposite interface shear strength (IFSS) with a surface energy of 70.30 % Sum 69.75 %. After the MOF, the effective CNF showed the interfacial ability, and the primary effect rate of 97.01 %. In the future, effective CNF is possible (Zhang, 2019). In the rGO-Ns-like rings made of oxide solution is vaporized and melted in parallel at 180 ℃, and solidified at 0.6 MPa. The developed nanocomposite rGO-Ns-epoxy), in which the graphene (Nitrogen) n-doped rGO-N is reduced with hydrazine via vapor phase method. The developed composite with different weight percent of rGO-Ns are attributed with improved mechanical and the effective performance (EMI) coverage (Shi et al., 2021). Consequently expression of the given rGO, the flexure performance is encountered by the addition rGO-Ns possible improvement in EMI suppression effect performance. GO has lower oxygen content as compared to rGO; showed an improved interfacial performance; which is caused by rGO-N doped porous like films (Deng, et al., 2021; Du, 2022).

In another work, MXene aramid fiber decorated 2D fibrous composites aerogel assembly was developed using simple dipping and solution casting method, The developed composite assembly with thickness of 2 mm and showed 80 % (SE) with reflection loss of 21.5 dB/mm (Wang et al., 2020). Typically carbon coated PVA fibers showed an effiecincy of composite materials have higher reflection loss and main electromagnetic interference. It is possible to move freely in the inner layer of the composite material, and the ability to cover the electromagnetic interference. (Yu et al., 2022). The rGO/PI-CNT composites were prepared by incorporating rGO into the PS polymer matrix as demonstrated in Fig. 18 (a & b). Similarly, the CNT-PU based paper was developed via electrodeposition method. The developed nano composites showed and effiecient EMI (SE) of 60.0-65.5 dB. The developed composite Bucky paper showed highly efficient shielding (SE) performance through a simple electro deposition approach. The designed composite Foam represented an outstanding shielding efficiency of 60–65.5 dB in X-band with minimum thickness of 100 um, which is best ever as compared to previously reported findings for MXene, CNT-PU and graphene-PI-Adamine based porous foam composites Fig. 18 (c & d) (Liu et al., 2021; Fan, 2021; Lu et al., 2021; Amini et al., 2021).

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Fig. 18

(a) Graphene based rGO/PVA aerogels nanocomposites aerogels foam structure reproduced with permission Elsevier 2021 (Fan et al., 2021), (b) carbon foam via PU impregination method; reproduced with the copyright permission of Elsevier (2022) (Sharma et al., 2022), (c) MXene and aramid nanofibers aerogels; reproduced with copyright permission by Elsevier 2021 Lu et al., 2021 and (d) Adenine –PI polymer and graphene foam for EMI (SE). Elsevier 2021 has granted permission to reproduce this Figure (Luo et al., 2021).

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Conductive polymer nanocomposites (PNCs) were prepared by adding Cu NSs to rGO/PS composites. The results also demonstrate that these PNCs have EMI shielding; the shielding efficiency of 36.0 dB at 8.0 GHz and 29.5 dB at 12.0 GHz. In the frequency range and percentage of fillers studied, the dominant protection mechanism was reflective. Eventhough, the distance between rGO membranes can be prolonged by using intercalation to improve the permeability (Thadathil et al., 2022). Achieving a uniform intercalation without the addition of fillers for porous media is under investigation, to increase the proliferation of EMI waves. The preparation of elastic porous films with high compressibility and facile fabrication processes is one of the most popular hotpots especially for electromagnetic shielding and microwave absorption is under investigation and still facing great challenges (Sang, 2022). Similarly, graphene and silver nanocomposites (rGO-AgNWs) as solgels and PU-hydrogels has been developed and used for improved EMI shielding. The developed nanocomposites are highly conductive, flexible, bendable, and are stretchable with improved tensile strength (Xu, 2021). The microwave and shielding performance (SE) of the graphene-based nanocomposites is also improved with the addition of different metal–organic frame works (MOF), with graphene oxide and reduced graphene oxide as shown in Fig. 19 (a-e). A novel and green one-step (In-Situ) thermal treatment approach have been used to fabricate the lightweight silver/rGO-coated melamine carbide (NFC/rGO/PU-PDMS) films and porous foams with superior mechanical properties and excellent EMI shielding effect (SE) (Wei, 2022). The NFC/rGO/PU-PDMS based MXene and graphene based polymer composites (MGP) foam exhibits excellent structural stability after 1000 load-unload compression test cycles; due to the enhanced interface of rGO between the NFC framework and silver nano particles showed better stability against mechanical detrition (Xin et al., 2021). However, graphene oxide (GO/MXene-PU) and rGO-MXenes based aerogels are encouraging materials for advanced applications for example; batteries, supercapacitors, filtration and electronic devices for microwave and EMI shielding; but still there is a great demand to improve the performance stability (Bai et al., 2020). Although; the interlayer distance of rGO-MXene-PU aerogels can be expanded by using intercalation to increase permeability, achieving uniform intercalation without the addition of fillers and removal from the porous media to improve the propagation of electromagnetic waves (Cao, 2019). The preparation of elastic porous films with high compressibility and facile fabrication processes is one of the most popular hotpots especially for EMI and MA is under exploration and facing great challenges. Similarly, graphene and silver nanocomposites (rGO-AgNWs) as solgels and PU-hydrogels has been developed and used for improved EMI shielding. The developed nanocomposites are highly conductive, flexible, bendable, and are stretchable with improved tensile strength. The microwave and shielding performance (SE) of the graphene-based nanocomposites is also improved with the addition of different metal–organic frame works (MOF), with GO and rGO (Sun, 2021; Srivastava and Manna, 2022). Another work was used to determine by practicing a novel method for the construction of graphene on micro-cellular level with epoxy and attained the long-lasting performance in the designing of the nanocomposites with dispersion of CNT in GO and epoxy resin to develop nanocomposites structures as shown in the Fig. 19 (a). The designed nanocomposite has been developed by utilizing a supercritical CO₂ foaming approach; in which the epoxy based composite was modified nanocomposite was effervesced showed a multiple boundaries and finely tunable cellular structures (Song, 2017; Zheng, 2021). Furthermore, the re-organization of nano filler during formation of foam structure which is reasonable with more intense conductive framework, and leading to improved microwave attenuation with higher dielectric loss and repeated reflection loss to improve the microwave absorption. The optimistic combination of electrical conductivity of 314 S m⁻¹ and effective shielding of 86.6 dB and 156.3 dB/(g/cm³) was attained with mechanical performance of (27.5–30 MPa) and density of (0.55 g cm⁻³) has been achieved for the foam structure of the resultant composite containing 30–32 % wt% of graphene as filler (Liu et al., 2016).

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Fig. 19

Process for fabricating MGPP composites (a), surface SEM images of  PU (b), PU@PDA (c),  MGP100 composite sponges  (d), and MGP100-3 composite sponges and their corresponding magnification images (e), reproduced with copyright materials by Springer (2022) (Jin et al., 2022).

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The research was used to develop a novel and lightweight carbon foam (CF) adorned with ZnO nanofibers (NF) for highly stable and improved EMI shielding. Initially, the carbon fibers (CF) were synthesized from a phenolic based resin using the polymer polyurethane (PU) to develop foam through an simple mixing method trailed by carbonization, and finally the CF were decorated with an electrospinning method (Jin et al., 2022). The (SE) and comparative multifaceted permittivity of the ornamented froths were studied by vector network analyzer in X band over a frequency range of (8.2–12.4 GHz) for a minimum thickness of 2.0 mm. It is revealed from the findings of experimental analysis, that the porous assembly of ZnO-NF can significantly improve overall EMI shielding effectiveness, with enhanced microwave absorption. The impedance matching and interfacial polarization delivered by the porous structure and ZnO nanofibers which leads to improve the EM wave absorption performance in CFs due to the decoration of ZnO on the surface of NF. The resultant CF exhibited excellent absorption-dominant with an EMI SE of 58.6 dB and a specific EMI SE of 1046 dB cm² g⁻¹ at only 0.28 g/cm³ density (Li, 2022; Liang, 2016).

Thus, the lightweight ZnO decorated CF is a promising material for aerospace and next-generation smart devices. Similarly, the work made on the production of porous carbon based foam structure showing an improved EMI performance was successfully designed from graphene oxide (GO) and adenine-polyamide fibers (Zhu et al., 2017). The development of graphene with conductive framework; which showed higher retention of EM waves with regulated conversion of nitrogen doped films to enhance the films porosity. Whereas, the graphitization was successfully made by the carbon layers; which resulted as an improved electrical conductivity of (0.22–0.55 S/Cm). the x-band valued to (8.5–12.5 GHz) as out performance shielding (SE) performance increased to 48.5 dB as well SSE to 8375.6 dB SSE (8370.8 dB cm³/g), and SSE/d (19789 dB cm²/g) (Gao, 2020). Moreover, the carbon based foams exhibited firmness towards cyclic retention and recover ability against the MA and EMI shielding capability in the organic solvents. The overall performance (SE) and microwave shielding enhanced with higher aspect ratio and filler content percent of 2D materials including (MXene), boron nitride (hBN), and graphene with epoxy resin as a binder (Wan et al., 2018; Wu et al., 2020). The significant effect of epoxy assists in self-assemble nanowires and developed nanocomposites decorated glass fibers could help in self-bridging and more conductive paths, towards improved, electrical, mechanical and shielding performance. More significantly, the developed aerogel retains a high EMI-shielding presentation of up to ∼45.2–65.0 dB, which may attribute to its unique assembly showing better electrical and thermal properties. Additionally, the EMI SE of the designed foam reaches up to 50.6 dB only at a density of 16 mg cm⁻³. The resultant composite has a stabilized specific surface area (SE) with as high as EMI shielding outperformance of 76.16 dB cm² g⁻¹ over a very lower content percent (Zhang, 2021; Nazir, 2018). In addition, the high disintegration temperature (T_d, 10 %) of 600 °C showed a great advantage as compared to previously reported PI-based composite materials. These characteristics endorse the prospective of CNT/graphene/PI foam as a lightweight, compact, and heat-resistant material, which can effectively shield EMI and absorb electromagnetic waves (Zhang, 2019, 2020; Zhang, 2020). Similarly, in previous studies a new method for high-performance shielding materials; by MWCNT homogenously in-situ synthesis with conductive polymers and pristine graphene. Whereas, the rGO sheets are connected with Ti₃C₂Tx films and loaded nanoparticles on the catalysis of nickel, copper, aluminum or silver layered; which can be directly covered into aerogels and can be applied on the carbon cloth as a binder-free approach as shown in Table 4.

3.1.3 Graphene polymer-based Aerogels/Hydrogels composites

Herein, acrylonitrile butadiene styrene (ABS) porous materials foamed by etching and post-etching supercritical CO₂ (SC-CO₂) was prepared and proposed for shielding effective utilization for electronic applications. The newly designed ABS porous and conductive composites were synthesized via addition of conductive filler of carbon black (CB) (Wu et al., 2017). The outcomes showed that, as the content percent of polyethylene oxide (PEO) was varied in the composite the overall SE performance was increased to 50 hrs. stability. As prepared ABS materials with a SC-CO₂ an open-cell with wider spacer structures after foaming and chemical etching. When the CB content reaches 6 %, the conductivity of the ABS porous material prepared by the etching method is 25.6 Sm⁻¹ after etching. The electrical performance of the ABS porous material foam/films was further improved to 150 Sm⁻¹ with EMI shielding performance of 23 dB. In brief, the electrical conductivity was greatly influenced and improved when the filler content percent was increased more than 6 %. The electrical conductivity of the ABS aperture materials prepared by the two folds of magnitude by using both of the methods reached to 150–650 Sm⁻¹, and the highest EMI shielding was reached 32–65 dB (Yang, 2021; Luo, 2022). The developed foam has great potential in electronic and EMI shielding presentations. A lightweight melamine–formaldehyde-based materials showing substantial EMI shielding properties; developed through a facile and green synthesis of conductive electroless silver (Ag) plating and Polydimethylsiloxane/SiO₂(PDMS/SiO₂) coating method composite (SiO₂@Ag@MF) foam. The results show that SiO₂@Ag@MF foam has excellent EMI shielding performance with an extreme shielding efficiency (SET) of 65 dB, with a lower density (0.014–0.019 g/cm³), and higher SP efficiency (due to the open-cell having more wider space and porous structure). The resultant composite demonstrated a higher conductivity for a silver-plated skeleton, (SSE _T) of 34.39 dB cm³ g⁻¹. At the same time, the syntactic foam is superhydrophobic, anti-corrosion and anti-fatigue properties due to PDMS and SiO₂ coating (Wu et al., 2017). The combination of carbon nanotubes and reduced graphene oxide as a lightweight and higher electrical conductivity with improved mechanical performance is acquiring higher demand for macro–micro scale graphene based composites, films, foam and aerogels. Therefore, the carbon nanotubes and graphene oxide as demonstrated in Fig. 20(a), are prepared by simple and cost effective method freeze-drying and in-situ catalytic growth methods (Gao et al., 2021; Luo, 2021). The carbon nanotubes and graphene based foams comprising of higher interconnection of rGO sheets with eachother through CNT as bridging groups to develop 3D structure, showing sifnificant growth towards EM and MA performance. Whereas, the graphene sheets has been grown on metallic and polymeric substrates. The in-situ progress conataining fraphene films laoded CNT leading to an enhanced EMI, shielding through conuctive paths, and defect induced polarization loss. The designed nanocomposite made from CNT/rGO showed greater interaction with rGO nanocomposite aa 3D hetero-structure developed via in-situ growth of CNT on rGO films (Zhang, 2019; Xu et al., 2022).

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Fig. 20

Preparation of graphene & carbon nanotubes (CNTs-rGO) and rGO/CNF@Ag-Fe₃O₄(rG-CF) porous film for EMI shielding application mechanism. Images were reproduced with the copyright materials by (a-Elsevier 2019 & b-Springer Nature 2020) (Guo et al., 2020; Kong, 2019), lightweight reduced graphene oxide, PDMS and flexibile cellulose derived Carbon aerogel (c). This figure has been reproduced with the copyright permission by Springer Nature (2021) (Song et al., 2021), and Carbon nanotube-PVF nanocomposites for EMI. (d). The Figure has been reproduced with the copyright permission by John Wiley and Sons 2021 (Dun et al., 2021).

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The composites foams made of CNTs/rGO with variable filler content percent of CNT in rGO are prepared to study the effect on EMI shielding properties over a variable range in X-Band. The effective shielding (SE) performance of composite was nearly 31.5–23.5 dB with minimum thickness of 2 mm; which reaches up to EMI-SE of 547.0 dB cm³/g having an ultra-light density of 55–57 mg/Cm⁻³. Additionally, the shielding efficiency (SE) was reached around 49.6 dB with variable size and thickness of 3.1 mm. The developed 3D porous structure as shown in Fig. 20 (a) shows a unique hierarchical structure and a light density with outstanding SE performance; it showed a auspicious and desireable approach for the design and development of CNTs/rGO composite foam for microwaves absorption and EMI shielding materials (Zhang et al., 2018). In addition the optimizing the of flexible and wearable CF-based materials has excessive prospective in the applied solicitation of EMI shielding. The presented work be responsible for comprehensions interpretation on the design and production of EMI shielding with broader application.

Furthermore, to elaborate the structural design of such microstructural materials is suitable and critical to obtain a cutting-edge EMI shielding effectiveness, which is obtained to make lightweight, highly flexible, durable, and processable. In brief, the genetic dielectric genes from rGO, including defects and functional groups, are identified, and the interfaces generated from Fe₃O₄ nanoparticles are dissected based on previous works. Through the tailoring of Fe₃O₄ content, temperature, and spatial distribution, the microwave absorption is flexibly adjusted, with a R_L of − 59 dB and a − 10 dB BW of ≈4 GHz. Significantly, benefiting from the synergy between the dielectric genes and the magnetic medium, the matching thickness is as low as 1.17 mm. These important results are a powerful supplement to basic knowledge of high-temperature electromagnetism, laying a foundation for the construction of electromagnetic functional materials and devices that adapts to the environment at elevated temperature (Zhou, et al., 2020; Zhao, 2018).

However, on the other hand, the relationship between the mechanical attributes as well as shielding effectiveness for EMI material are related; especially based structural orientation and hierarchal composition of an ultrathin and porous assemblies based composites for suitable end uses. The work presented on light weight and highly flexible rGO base composites of rGO/CNF@Ag–Fe₃O₄ (RGCF) as porous media for efficient EMI shielding application as shown in Fig. 20 (b). The assembly was designed using most widely used technique; vacuum filtration approach after chemical and thermal reduction. The graphene carbon fiber based porous structure exhibited an outstanding mechanical performance with tensile strength of 175.5 MPa, and composite showed a light weight RGCF as porous films with 20–21.0 dB; which much better than the compact films having 10.5 dB and an efficient wave attenuation properties on single cell level. Therefore, the highly flexible and light weight RG-CF as porous film with applicable EMI range of SE performance over a superior mechanical tensile strength as a promising candidate for smart and flexible wearable electronics (Zhao, 2018; Ryu, 2022).

Similarly cellulose based cotton composite fabric showing higher chemical bonding to develop a self-assembly of cellulose acetate (CA) self-assembly loaded with (NaOH) solution, subsequently developed via gelation and free drying method. Later on, the cellulose coated carbon fiber based aerogels covered the surface by rGO to develop CA/rGO aerogels are prepared via vacuum filtration followed by freeze dyring and thermal reduction respectively. Finally, the CA-rGO covered with PDMS polymer towards an improved EMI shielding effectiveness of the composite are prepared through back filling of PDMS in polymer matrix. The designed structure owing to skin-core structure made up of CA@rGO, as porous (3D) structure coated with double-layer of graphene as conductive network was successfully constructed as shown in Fig. 20 (c) (Lan, 2022; Zhao, 2018). The study revealed that, the loading of rGO content percent of 3.5 % with CA over rGO and PDMS showed an exceptional EMI shielding performance (SE) 50–52 dB, which around four times greater as compared with the co-mixed CA-rGO and PDMS for microwave and EMI shielding of 13 dB loaded with same filler content percent. Similarly, the CA@rGO/PDMS composites showed an excellent thermal stability and thermal conductivity having coefficient (λ) of 0.65 W m⁻¹ K-1 (Lan, 2022). The resultant assembly showed an excellent performance for CA@rGO/PDMS with EMI shielding of 12.5 dB for designed composites; which showed a great outlook for potential end use applications as highly efficient and lightweight EMI shielding composite material. A porous foam composite was made from poly(vinylidene fluoride) (PVDF) loaded with carbon nanotubes (CNTs) was developed for EMI shielding by using a solid-state supercritical CO₂ foaming approach has been made so far. The. PVDF was selected as a matrix due to its extra ordinary features and an excellent chemical resistance, thermal stability, and flame retardancy. The incorporation of CNT enabled the composite viscosity and high modulus which at most twice greater than the pure and barely used PVDF as shown in Fig. 20 (d) (Lan, 2022). The EMI precise defensive efficiency of an acquired foams could reached the optimal significance of 0.024 S m⁻¹ and 29.1 dB cm³ g⁻¹, individually, whereas, the instigating from the ongoing expansion of consistent CNTs and conductive network on the cellular assembly as porous media of the PVDF matrix. Stimulatingly, the orientation of CNTs triggered by frothing development marks in percolation threshold of PVDF/CNTs decreased with comparison to the un-foam based samples (Luo, 2022). The carbon fiber with MoS₂-carbon fiber (MoS₂-CNF) aggregates were produced for the first time by embedding WS₂. The designed heterogeneous assembly demonstrated the several imperfections on the exterior of carbon fiber (CF) by by means of a simple one-step hydrothermal method. The nanocomposite assembly was used to protect electronic equipment from electromagnetic waves on broader level. The (SE) performance of MoS₂-CNF was expressively enriched, exclusively for the S and C bands and was found to be highly stable against the propagation of thermal and electromagnetic waves up-to a broader range of 2–18 GHz. The typically several parameters including size, thickness of 3.00 mm showed an EMI shielding efficiency of 36.0 dB, which higher than the barely used pristine CF (25.5 dB) as shown in the Fig. 21 (a-e). The sheiding performance of different organic compounds with different polymeric susbtances are presented in Table 5 (Shi et al., 2017; Xu, 2021).

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Fig. 21

Large Scaleable fabrication of MXene based Fabrics(a), sheet resistance response (b), thermo-response (c), shielding mecahanism (d), and multiple layered reflection and polarization of developed composite assembly (e). Reproduced with copyright materials, Springer 2022 (Zeng et al., 2022).

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Similarly, the tree-dimensional (3D) hierarchical composition of 2D materials as porous scaffolds may also be integrated with silver nanowires (AgNWs) and polyurethane (PU) by mimicking natural leather by using a simple dip coating method over an ambient temperature (Zhao et al., 2017). The consistent micron-scale cavities and distinctive covered construction of such nanocomposites facilitate the homogenously attached AgNWs and greater protective presentation by considerably aggregate the absorption loss of (98.5 %). remarkably, the leather-like combination demonstrates the paramount EMI shielding effect ranging (∼110 dB) from 8.2 to 12.4 GHz) as compared to the natural leather-based materials reported in previous works. In addition, three dimensional (3D) and polyurethane-PU PDMS and CA with CNT and graphene with variable filler loading and thickness towards improved EMI Sheilding (SE) are demonstrated (Liang, 2021). Making these composite stable and durable EMI shielding goods; that could withstand and restrict the ultrasonic, alkali, tape peeling, bending and abrasion resistance (Zhao, 2018). Graphene and polymer based composites have the advantages of light weight, informal handling, and outstanding electrical conductivity, and are encouraging entrants as well-designed EMI shielding materials. The conductive polymer are related to a type of materials which are majorly based on reflection loss (R_L) and comprising of several advantages for example enhanced electrical conductivity and obviously improved shielding effect and absorption performance. The functionalization and surface modifications are considered as critical factor and important factor during the synthesis and designing an effective shielding (SE). There are several studies has been made to improve shielding performances with addition of different fillers in conductive polymers (Shayesteh Zeraati et al., 2021). So, rather a low fillers content percent is required in the nanocomposites not exceeding 10.0–20 by wt% of the composite assembly and a very high level of thickness of 2.0–2.5 mm, can be achieved to work better and optimize the nanocomposites M@GAMS with a reflection loss (R_L) of − 49.1 dB with a variable frequency range of 14.2–18.0 GHz. Therefore, the scalable technology is needed to reduce electromagnetic pollution from low-density and low-carbon footprint materials. Unfortunately, in most electromagnetic shielding materials, environmental adaptability, economic feasibility and light weight are far from these optimal factors (Li, 2017).

3.1.4 Graphene ICPs Polymer-based composites

The incorporation of dielectric and magnetic mechanism is an auspicious approach for the fabricating of EMI shielding materials with exceptional attributes. In order to further improve the shielding ability; while preserving extraordinary fascination presentation and its practical submission with an advanced shielding material (EMI) are instantly involves sensible and comprehensive organizational design (Cao, 2018). In this work, exceedingly permeable and porous nickel based foam (NF) with a macro to micro level builds to develop conductive framework. Then, the polyaniline (PANI) was successfully loaded on the surface of fibrous assembly NF by using a simple in situ fabrication approach. In another study made on addition of small fraction of polyvinyl alcohol (PVA) was used an adhesive, on the graphene (rGO/MXene). When the rGO loaded polymer was produced by using a spun lace non-woven fabric (SNF) technique, in which initially soaked and then dried soaking-drying consequently thermal and chemical reduction technique has been reported so far, the design of the sandwich structure wherein, the SNF sheet was covered with rGO/MXene asupper and lower deposited with polymer Nano woven sheet as interlayer (Han et al., 2021). The outperformance related toward the EMI shielding effectiveness (SE), having good electrical, thermal and mechanical stability were perceive. On the other hand, the performance is attributed as highly efficient with multifunctional attributes for example the flame retardancy of the fabricated sandwich structure has been investigated. It is revealed from, the results that, when the mass fraction of rGO to MXene was 6:4 the reached to an average SE_T of 55.8 dB for X-band and also increased the absorption shielding when applied to a voltage of 4.0 V volts to rGO/MXene composite films, The temperature on the surface was exceeded to 110 °C within 10 s, which shows that the fabricated composite film can be functional application including enhanced electromagnetic shielding device with outstanding performance as demonstrated in Fig. 22 (a-c) (He, 2021; Xu, 2019). Similarly, the nanofibers NF/PANF with distinctive (3D) porous heterostructures were created. Even though the thickness is only increased by 2.7 % as compared to original NF, the shielding efficiency of the NPF assembly was greatly influenced and significantly enhanced and reached up to 93.8 dB which can shield ∼ 99.96 % of released incident waves as radiation. In precise, among the previously reported shielding materials, NPF has excellent absorption loss per unit thickness characteristics (147.64 dB/mm) (Zhang, 2022). This extraordinary performance can be attributed to 3DPorous heterostructures, existence of plentiful boundaries, and dielectric-magnetic incorporation in NPFs (Liang, 2021). These properties greatly expand interfacial polarization, dielectric, dipole relaxation, decay constant, and multiple reflections as shown in Fig. 22 (d-f). In brief, the power balance and differentiation among the absorption and reflection attributes of the assembly shows that the waves absorption leads the shielding mechanism. The outstanding widespread shielding ability makes this heterostructure promising for electronic devices. In addition, prototypes for highly efficient and an effective shielding 3D porous heterostructures are studies for last several decades (Zhou, 2020).

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Fig. 22

Graphene porous films coated MXene coated CNF fibrous assembly design model l for microwave mechanism (a), SEM and digital image of graphene porous films coated MXene coated fibrous films (b), porous MXene and Graphene films with SNF fibers as middle layer covered surface (c), thermal conductivity of MXene with variable wt% (d), effect of temperature on electrical performance of developed fibrous films (e), and SE efficiency of develop fibrous fabric with different rGO and MXene content percent (f). Reproduced with permission of copy right material Elsevier 2022 (Zhang et al., 2022).

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3.1.5 Graphene/MXene-conductive polymer-based composites

The synthesis techniques used to modify and etching of the MXene structural and functional properties from MX-phase to MXene and their nanocomposites are widely achieved by a combination of different polymers and intrinsic conductive polymers to meet the requirements. The developed nanocomposite showed robust mechanical, hydrophobic and heat insulation towards durable and stable PMMA use without any deformation of the developed aerogel in variable temperature, humid environments. Presently, selection of various metal and non-metal based fillers has been put into practice with conductive polymers. Similarly, the use of intrinsic conducting polymer (ICPs) materials is more reliable and can be used to form highly conductive composites by converting conjugated π-bond polymers into conductors via chemical doping as shown in Fig. 23 (a-e). The results indicate that the total shielding (SE_T), SE_A and SA_R of the doped PPy and composites have a SE_T value of 79.9 dB. Further more significantly, the subsequent EMI shielding constituents are primarily recognized from an absorption loss (SE_A). The different kind of filler showed great influence on the SE of the developed PPy-rGO based composites. Similar works related to EMI shielding with some other polymeric compounds polyimide(PI) has been reported in another study, without using any binder or thickness used with GO and MXene nanocomposites.

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Fig. 23

MWCNT crossectional view of carbon nanotubes as capacitance mode interconnected with each other, schematic of the microwave performance of composites (a), microwave absorption performance of a multi-dimensional assembly achieved by enhanced dielectric relaxation (b), ultralow percolation threshold and EMI shielding multi-walled carbon nanotube nanocomposites (c), with electrically conductive segregated networks (d), PLA-CNT porous films with variable content percent of CNT by Wt% (e). The image was reproduced with MDPI's copyright permission, 2021 (Huang et al., 2021).

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The newly developed robust composite showed better performance as compared to pristine GO-PES and MXene films with maximum EMI shielding response of 12.5–1.0 dB. Whereas, the higher stability and exceptional thermal conductivity as well as electrical conductivity reported with the developed rGO/MXene/PI composite aerogels. The exclusive and distinctive chemical, physical and thermal properties were obtained, when the polymer showed an enhanced bonding and better interactions between GO, MXene nanosheets with PI polymer based precursors (Huang et al., 2019). The resultant 3D structural assembly elaborated improved EMI shielding efficiency over a wide range of microwaves. Therefore, the designed 3D porous assembly showed better feature and considered as a distinguishing material. Similarly, in other work, the graphene and polymer composites (GMP) aerogels were prepared using a with layered structure followed by a directional freeze drying method. The developed hetero structure have a low power density (8.97–12.71 mg/cm³), higher electrical conductivity (3.08 S/m), and incredible adjustable compression and fatigue resistance of (90 %) against 5000–10,000 loading and unloading of the composites (Elmobarak et al., 2017; Kim et al., 2019). Several studies have been reported on the designing of mesoporous, nano-porous and macroporous nano-hybrids with different conductive polymers for the synthesis of hydrogels and aerogels. Such microspheres are designed with the addition of Nanoparticlulates in the polymeric substances with greater emphasis on graphene, graphene oxide (GO), reduced graphene oxide (rGO) and Ti₃C₂T_x MXene by rapid ice-freezing technique. Collectively; the core-sheath nano-porous assemblies are attained by incorporation of different metallic particles, with the disparities to develop pores in the conductive polymer/rGO and Ti₃C₂T_x MXene as separated apart from the nanostructures using phase separation techniques (Cao, 2021). A very fine and Lightweight, highly flexible, and conductive porous films were designed from graphene nanosheets, with wider opening of the GO films after chemical and thermal annealing. Therefore, the researchers practiced in several studies mechanically strong, highly flexible and electrically conductive porous films of the reduced graphene oxide (rGO)-Ti₃C₂T_x MXene (rG-M) in the form a regular morphological shape of the films by a chemical treatment with hydrazine as reducing agent being used in the synthesis and reduction process. The presence of MXene in the developed composite assisted in prevention of an extreme enlargement of the rGO- with MXene films as demonstrated in Fig. 24 (a-e) (Xu, 2021).

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Fig. 24

Development of MXene-rGO films via filteration and foaming developed composite (a & b), SEM images and model design for porous rGO-MXene films with excess foaming (c), controlled foaming (d), and mechanical performance of composites films (e). Repriduced with copyright materials by Springer Nature. 2022 (Zhang et al., 2022).

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The resultant composites also enhanced the electronic properties, which is due to the availability of conduction channels among the rGO and MXene films, and resulted with an enhanced thermo-mechanical attributes (Xu, 2021). The resultant rGO-MXene films presented highly greater EMI-SE properties as well as mechanical stability of highest tensile strengths (24.5 MPa) among the porous films. These out performances are compared to pristine films of rGO counterpart, and MXene counterparts exhibited an electrical conductivity of 74.4 S·cm⁻¹, and exceptional broadband EMI defensive ranging from 8 to 26.5 GHz (Saghlatoon et al., 2014). At most higher performance towards EMI-SE of 52.5 dB was accomplished by regulating its wideness and handling technique, as long as a practicable production course for inconsequential and highly suitable EMI-performance materials. Similarly, the carbon aerogels with ultra-low density and high mechanical properties were successfully prepared by the GO in the liquid form and crystal formation after reduction with stabile reinforced composites with cellulose nanofibers (CNFs) (Simorangkir et al., 2017). Combination of CNFs into GO and as reduced into rGO nanosheets enrich the interface between rGO nanosheets and CNT without and with using binder, thickeners which could work as soldering effect, thereby limiting the sliding of rGO nanosheets and the separation between microspheres, thereby significantly improving the mechanical properties performance (Rizwan et al., 2017; Razaq et al., 2018).

3.2.1 MXene-CNT polymer-based composites

Similiarly in stuy researcher team established a mild hydrothermal technique to assemble 2D MXene into 3D architecture which can act as the conducting pathway for polymer nanocomposite. They synthesized Ti₃C₂T_X MXene through HF etching method and systematically investigated how filler loading, coating thickness influence the dielectric properties and microwave absorption ability from 2 to 18 GHz. The resultant MXene-rGO based aerogel collective with the well reserved essential structure of MXene and aligned core–shell structure, shows promising electrical conductivity as high as 1085 S m⁻¹. When used as conductive networks in shielding materials, the aerogel endows epoxy nanocomposite with remarkable electrical conductivity (695.9 S m⁻¹), and EMI-SE of the nanocomposite exceeds 50 dB; with a determined rate of 56.4 dB over X-band (Iqbal, 2020; Han, 2020).

The electrochemical property was significantly enhanced due to the CNT supporting the original multilayer structure of MXene, bridged the pathways for electron transport between each particle, and providing extra-ordinary performance toward shielding effectiveness as shown in Fig. 32 (a–c). The design and development of a highly efficient MA material for electromagnetic fortification have established extensive consideration. The recent progress and dielectric microwave absorption materials become a research direction for development of new material and the complementary use as a function to study the mechanisms of synergistic loss. In addition, the compact structures of MXene films are wide-open to surface area from reduced complex compositions. Several unique composites are consistently grown-up with MWCNTs and carbon cloth (CC)‐reinforced with MXene sheets (CC-MX). The results of rGO-MXene@BC discloses the synergistic amalgamation of chemically exfoliated large surface area having an excellent electrical conductivity and SE over a variable w% of rGO in MXene as shown in Fig. 32 (d–f) (Han, 2020; Xie, et al., 2019).

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Fig. 32

EMI shielding performance of CoNi@AirTiO₂ based segregated nanocomposites (a) & EMI response under compressible graphene foam (b), Ultralight and flexible developed assembly (c), EMI) response (d), chemical etching of MX-Phase into MXene (e), and flame retardancy/hydrophobic property of the developed MXene based composite assembly (f). Reproduced with permission of the Royal Society of Chemistry, copyright 2021 (Wang et al., 2021).

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Modern microelectronic devices urgently need functional composite films with great EMI shielding and light-to-heat conversion properties, especially for use in extreme environments. Here, by incorporating 1-D AgNWs and 2-D MXene into a nanocomposite heterostructure, with (PVP) polymer based assembly. The light weight and flexible Poly urethane with MXene and silver nanowires (MX-AgNWs/PU) foam and films were developed for EMI and light to heat conversion solar cells. The developed 3D porous assembly of AgNWs and MXene showed improved multiple interphase with SE of 45–50 dB at minimum density of 0.15 g/cm³ for X-band as demonstrated in Fig. 33 (a-d) respectively (Weng, 2020; Zhao et al., 2017).

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Fig. 33

Simulated model for EMI sheilding mechanism of graphene films (a), reproduced with permission to copyright materials by Elsevier 2021, (Zhang et al., 2021); chemically modified MXene-BC films with total (SE) (b), reproduced with permission; Copyright 2021, ACS (Wan et al., 2021); EMW absorption with dielectric loss and reflection loss in rGO-MXene skeleton loaded with Ni-nanochains (c), and reflecton loss of developd composite assembly via freeze drying (d) for electromagnetic shielding (EMI) SE mechanism Reproduced with permission; Copyright 2021, ACS (Liang et al., 2021).

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3.2.2 MXene and polymer based aerogels/hydrogels/Foams

The synthesis and fabrication of ultra-fine, highly flexible and mechanically robust MXene films is still under growth and requires certain developments. The use of MXene films with different natural polymers for example bacterial cellulose has been made to develop flexible and very fine films produced via mass scale production using in-situ bio-processing technique. The sheets are well oriented and fine-tuned during the synthesis stage, to formulate the MXene-BC nanocomposite network with highly entangled nano-cellulose (Wan et al., 2021). However, several biomass drived carbonous compounds (BC) has been developed as porous structural arrays. Here, a novel biomass carbon was developed from soyabean bregs, followed by chemical (KOH) treatment and sequencial hydrothermal treatment. The developed biomass–carbon foam structure showed a significant enriched precise surface area which assists in charge transmission channels, and more conductive paths. As a result, the sponge structures showed an increased multi-direction reflections and scattering As a multiple loss and due to a better-quality impedance matching, leading to an enhancement of EMW absorption performances. The acquired single-component based carbonous foams having without any practical filler demonstrating an operative EMW absorption proficiency over a wide range absorption band width of 4.8 GHz with a thickness of 3.5 mm. The developed resultant 3D assembly exhibits long lasting performance towards EMI shielding as well as mechanical stability with tensile strength of 295–297 MPa; when loaded with 20–25 % of MXene by weight. More importantly, a composite film with 4 μm thickness of BC with 74.9 wt% reveals a specific shielding efficiency (SE of 29141 dB cm² g⁻¹, which is greater than, the previously reported MXene and polymer based composites. The variable filler content of MXene and other carbon-based polymeric compounds composites showed that the facile fabrication could benefit an enhanced SE and mechanical performance (Lei et al., 2020). The designed composite assembly is environmentally friendly and can be fabricated using several scalable fabrication methods to produce ultrathin, very strong, and highly flexible material for example, the freestanding Ti₃C₂T_x/BC for efficient EMI shielding as presented in Fig. 34 (a & b) (Wei et al., 2020).

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Fig. 34

Electrical conductivity (a), EMI-SE of CG@CFA composites with various CNT/GO contents (b), comparision of EMI SE of CG@CPA composites and other reported composites (c), comparision on SET, SEA and SER of CG@CPA composites. Copied with permission Copyright 2021, Springer (Wang, 2021).

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Similarly, a 3D nanostructure made of MXene/reduced graphene oxide (rGO) aerogels attached with nickel Ni nanoparticles and wires were produced by using directional-freezing, soft template, Simple dip coating, and thermal anealing methods (Li, 2017). The as prepared composites films contains GO, were subsequently reduced with hydrazine hydrate and other reducing agents under inert environment as well vapor reduction process. The designed composite contains the highly oriented cell structure as heterogeneous nature, which results in dielectric/magnetic loss and interfaces (Ma, 2020). The metallic and reduced graphene (M−rGO) based nanocomposite could benefit the higher MA and EMI shielding performance with perfect impedance matching, multiple polarizations, and electric/magnetic-coupling (Zhou, 2020). Remarkably, the equipped under ultralight Ni/MXene/rGO (NiMR-H) aerogels with density of (6.45 mg cm⁻³) and delivered with the best EMI presentation in previously informed MXene-based fascinating constituents with a insignificant replication loss (R_Lmin) of − 75.2 dB (99.9 %) MA and larger EAB of 7.3 GHz respectively (Zhou, 2020). The designed heterostructure showed an improved SE of 85.8 % The synergistic effect of the MXene and WPU based foam exhibited an improved shielding effectiveness of 60 dB with addition of AgNWs and absorption performance was reached to 95 %, The foam structure showed better stability against heat, compression, under variable cycles. In addition, the syntactic foam structure also capable to convert the heat into electrical energy harvesting and other related fields for multiple purposes (Cui, 2019; Zhou et al., 2020; Xin et al., 2019). The developed flexible and light weight MX-AgNWs/PU films and foam could provide better solution and facile approach for EMI and MA, photothermal and heat energy conversion in military, aerosspace and wearable electronics (Cao et al., 2019). The study is based on revealing electrical conductivity (σ) and shielding efficiency (SE) values of rGMH/epoxy nanocomposites by increasing the filler, shape & size of honeycomb unit cell as shown in Fig. 34 (c & d) (Wei et al., 2020).

The shielding effective performance was attained; by variable wt% of fillers rGO and AgNWs covered with MXene sheets, in epoxy nanocomposites by directly blend ding as filler. Similar to these studies on different conductive polymer are also loaded with variable content percent of (GO), MXene, and silver nanowires (AgNPs) for the development of light weight and porous graphene based hydrogels towards the microwave shielding over a high frequency of 2–18 GHz (Cao et al., 2019). In the meantime, the obtained MXene/rGO based porous nanocomposite structures including foams, films and fibrous structures are more hydrophobic than Ti₃C₂T_x film, which is favorable during the reduction process as during reduction the oxidation caused by water agglomeration on the surface (He et al., 2020). Whereas, the prepared MXene/rGO porous composite structure showed superior thermal stability, electrical conductivity & EMI shielding performance. The EMI shielding materials are demonstrated in Table 6.

In general, the as generated heterostructures covers the greater area and interacted due to the surface functional moieties present on the films or edges of the rGO and MXene sheets as reactive groups. Heterogeneous silicone silver-coated glass fibers (Ag@GF)/MWCNT/ferrous oxide (Fe₃O₄) syntactic foam. SC-CO₂) bubbling. Due to a reasonable dissipation mechanism, the average EMI -SE) efficiency and MA measurements of 78.6 dB and 0.82 respectively as demonstrated in Fig. 35 (a & b). The significance in confirmation fashioned and come across by instance for both of the replicated electromagnetic and incident waves.The performance is further improved to 94 % absorption at 7.68 GHz (Vural, 2018). In another work presented on EM and MA based on MXene and nickel composite; with 1D nanowires of nickel (Ni) and 2D material MXene nanofilms has been developed. The developed composite assembly showed an exceptional attributes for the MA and EMI shielding effectiveness (SE) with a minimum reflection (R_L) of 49.5 dB was attained with a mild thickness of 1.75 mm over a frequency range of 11.9–18 GHz. As the filler content percent of Ni was improved in the MXene composite, showed significant raise in the SE of 59.9 dB which further enhanced to 66.9 dB by using at least 50 % by wt. The resultant assembly showed a absorption effectiveness of (SE) of around 60.0 dB as demonstrated in Fig. 35 (c) (Shi et al., 2021; Liu et al., 2018). It is also revealed from furthermore studies, that the better microwave and EM shielding performance is related with the synergistic effect of conductive paths of MXene; and hetero junction through soldering of nickel nanowires. The magnetic properties are attributed to nickel Ni which greatly imparted effect on dielectric loss and electromagnetic losses. These attributes can be fine-tuned and altered by using appropriate dosing of filler in the MXene assembly as well as processing operational parameters to tune the depiction or absorption of electromagnetic waves (Sang, 2022; Luo et al., 2019).

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Fig. 35

EMI shielding reflection loss of Nickel over MXene self-assembly via thermal decomposition (a), EMI-s SE total over variable frequency range with different Ni content%, and thickness (b), and design model showing EMI shielding mechanism of MXene sheets (c). Reproduced with permission; Copyright 2021, RSC (Deng et al., 2021).

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The synthatic foam reveals an admirable EMI shielding stability under multiple bending of the incident waves. This syntactic foam has wide-ranging solicitation predictions of electromagnetic fortification for wearable portable gadgets and can be used for fifth-generation communication appliances. In this case, the method is equipped with a simple method. EMI-SE with a thickness of 1 mm and thin film EMI-SE with 36 dB of X-wave stage, special cause of electromagnetic wave absorption from the other manifestation (SE) for 32 min (Sang, 2022). Processing of PVA thin film had great expression for crack healing characteristics, with higher tear extension rate of 160 %. The MXene inks has significant progress towards EMI and MA materials loaded with Fe₃O₄ particles having several advantages in electromagnetic SE performance by addition to ternary MXene/graphene@Fe₃O₄ composition. The developed MXene and GO based carbonous porous 3D composites as shown in Fig. 35 (a–c) (Wang et al., 2019). The use of traditional materials for example single-phase Ni, silver (Ag) and copper materials exhibits extraordinary ferromagnetic comportment, and dielectric and magnetic loss, which are key considerations for an efficient EMW absorbing materials. Though, underneath the accomplishment of EMWs, particularly in the GHz frequency range of X-band, Nickel nano-materials lean towards to produce a eddy current loss this effect, confines their potential end uses and application. Still there is great demand and higher interest for modification of these composite materials through their hierarchal structures during preparation and synthesis, as traditional single phase and multiphase carbon materials which are considered as an efficient materials and are widely used in various fields due to their light weight and superior conductivity (Zhou et al., 2019).

Therefore, the evaluation and design principles of the such matrix material to fabricate composites towards MW absorbing properties of the EMW-shielding is key consideration in which the shape and size are fine-tuned from 0D to 3D structures with carbonous compounds for example (carbon black, carbon nanotubes, carbon fiber, graphite oxide, reduced graphene oxide, and biomedical carbon) (Ameri et al., 2022; Zhou et al., 2019). Therefore, the designs of the composite as a matrix material are considered in various studies; to fabricate composites with metals, metal oxides, or polymer materials to obtain carbon-containing absorbing materials. However, the main purpose and ultimate goal of developing such light weight microwave absorbing and shielding materials composed of Ni-MXene and Ni-Graphene and carbon materials are the key target for design with high efficiency (EMW) absorption (Cao et al., 2021). The results showed an increased mechanical stability and elastic–plastic recovery material; and were foundto be suitable for electromagnetic waves in multi-order reflection. The study reveals that, with the increase and decrease of filler content percent of rGO and MXene in polymer PVA thin film, as flexible electronic sheets, the EMI shielding of the developed materials was greatly influenced (Liu, et al., 2020).

Another work study focused on restacking issue was addressed and resolved by opening up the restacked layers of MXene and graphene films loaded with silver nanowires and epoxy-based nanocomposites. In this concern, the most and widely used technique is the freeze-drying approach for creating porous and impermeable membranes of rGO films decorated with silver nanowires and MXene sheets in the conductive polymer for the proposed application (Liu, 2020). Some other techniques have also been reported in previous studies through instantaneous photo thermal gasification in water, to develop hydrogels filled with water in the interlayers and introduced reactive functional surface groups as shown in Fig. 36 (a & b).

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Fig. 36

FeCO-rGO/WPU waterborne polyurethanes based nanocomposites Film and its SEM image toward EMI sheilidng properties of films (a), shielding design model and Microwaves absorption properties of rGO@ FeCO layered assembly with atomic level microwave absorption behavior of graphene film (b), WPU-rGO/FeCo assembly in crossectional view (c), shielding mechanism for layered assembly covered in two layers (d). Reproduced with permission; Copyright 2019, Elsevier (Zhu et al., 2019).

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The two-dimensional nanomaterials have fascinated wide-range of contemplations in the present investigation due to their distinctive properties among various two-dimensional materials. MXene is a new type of material which is been widely used for the water, air filtration, energy storageand other electronic applications, due to its excellent surface enhancement properties, it has shown great potential in microwave performance (Zhang, 2020). Very fine and an effective EMI shielding material has been designed with waterborne polyurethane (WPU) composite films MXene and rGO for low microwave reflection loss. As pure MXene and graphene are considered by fabricating with ferric carboxide (FeCo) metal alloys for the embellishment of graphene (FeCo@rGO) and Ag nanoparticles as a layered structure (Weng, 2018). The composite assembly was molded by simple sedimentation technique with polymer(WPU). The produced film acted as a MA layer, and the ultra-fine particles of Ag layer covered the entire surface of the polymer which served as a highly efficient shielding layer as presented in Fig. 36 (c & d).

This distinctive layered structure comprises the microwave-reflecting attributes of nano Ag and the MA behavior of rGO@FeCo to a accomplish robust MA and EMI-SE performance with low reflection loss. The composite assembly has acquired significant improvements over a filler content of (10 wt% rGO@FeCo) with silver nanoparticles as a layer of 500 μm, to 300 μm in its thickness. The developed composite assembly of (Ag/rGO@FeCo/WPU) possesses an outstanding EMI-SE of 50.5 dB and the microwave reflection coefficient of 0.49 with an average SE_R of 3.2 dB) (Xiang, 2019; Liu, 2020). The results reveal that, the structure is potentially strategy and new method for flexible EMI materials with low reflection characteristics.

In general, the as generated hetero-structures covers the greater area and interacted with each other due to the surface functional moieties present on the films or edges of the rGO and MXene sheets. Whereas as the reactive groups are attributed to develop such mesoporous assemblies made from graphene foams. The MXene@GO based hybrid aerogels are converted into porous aerogels; in which the microspheres (M@PDMS) exhibit higher level of impedance with an improved MA and shielding performance (Wan et al., 2018; Liu, 2020). On contrary, the attributes of such developed mesoporous assemblies from graphene foams, MXene@GO based hybrid aerogels are converted into porous aerogels; in which the microspheres (M@GAMS) exhibits higher level of impedance matching with an improved MA and shielding performance as presented in Fig. 37 (a & b).

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Fig. 37

Developoment of MXene aerogels via surfactants (a), SEM images of MXene aerogels (b), MXene aerogels and bidirectional freeze-casting of MXene aerogels (c), and SEM image of a free-standing MX-phase exfoliated into MXene on Cu plate with PDMS and SEM image of the developed MXene aerogels (d) development Microwave shielding. Reproduced with permission; Copyright 2022, Wiley Online reproduced with copyright materials, Wiley online (Wu et al., 2020).

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Beside, this the developed hydrogels, aerogels, and sol-gels not only offers the porosity but are also assists in less reflection, dissipation or delocalization of incident waves; which is only possible through attenuating of the conductive paths for the enhanced MA and SE performance. The electrically conductive 2D fibre-based porous assemblies with excellent mechanical flexibility and electrochemical properties are considered as promising candidates for flexible electrode materials, but the key challenge is to improve the MA performance by the addition of filler and geometrical alignment of 2D sheets for potential applications of MXene coated fabrics as shown in Fig. 37 (c & d) (Wan et al., 2018; Fan, 2020). So, rather than the structural arrangements, the low fillers content percent is required during the loading of nanoparticles in the nanocomposites; which should not exceeding 10.0–20% by weight % of the composite assembly and a very higher level of thickness of 2.0–2.5 mm, can be achieved to work better and optimize reflection loss (R_L) of − 49.1 dB at a variable range of frequencies 14.2–18.0 GHz for M@GAMS. However the scalable fabrication technology is needed to reduce electromagnetic pollution from low-density and low-carbon footprint materials. Unfortunately, in most of the EMI shielding materials, environmental adaptability, economic feasibility and lightweight are far from these optimal factors (Liu, et al., 2020).

3.2.3 MXene and ICPs polymer-based nanocomposites

The MXene nanosheets were intended under a least level temperature by using an in-situ synthesis with a conductive polymer to develop nanocomposites. The micro scale assemblies of electrochemical properties. The metal carbides (Ti₃C₂/PPy) nanocomposites with variable mass fractions of PPy and Ti₃C₂ were considered for suitable shielding materials as nanocomposites. Remarkably, the higher specific capacitance and unresolved cycling permanence are principally recognized to the arrangement of organ-like MXene nanosheets; in the form of double-layered capacitance (EDLCs) and PPy showed higher pseudo capacitance performance, which proceeds the upgradation of the synergistic consequence amongst dissimilar electrode made of two different ingredients and diverse features of the instruments to improve the electrochemical routine (Feng, 2020). The designing of MXene-based materials for particular use of EMI shielding is reported in several studies in the literature. As the MXene are formulated with different compounds and having an excellent mechanical, thermal and electrical properties. Therefore, here a highly robust, flexible and durable MXene/carbon fiber(CFf) based fabric has been introduced which is blended with thermoplastic polyurethanes (MXene/CFf/TPU) composite. The developed composites were fabricated through simple electro hydrodynamic atomization deposition, layer-by-layer and hot pressing methods as demonstrated in Fig. 38 (a-d) (Miao, et al., 2020). However, in these compounds, the synergistic effect is attributes to van-der Waals forces and covalent bonds. These attributes resulted as increased tensile strength and out performance of the newly formed composite up to170.5 MPa, which is better performance as compared to pristine MXene and its composites as previously reported in literature. Additional, to this the EMI shielding performance of the designed assembly of MXene on carbon fibers loaded with thermoplastic polyurethane (MXene/CFf/TPU) composite was also enhanced with MXene and its mass fraction (Li et al., 2020; Liu, 2017). The overall stability and SE performance were reached to 40.5 dB, which is attribute to the dielectric loss. This synergistic effect may be introduced due to the presence of the conductive channels and the improved MA in the sandwich structure of the composites. More remarkably, the composite engaged an excellent resistance stability; EMI-SE stability and flexibility, even after multiple bending and releasing cycles as shown in Fig. 38 (e & f).

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Fig. 38

MXene coated fibers and thermoplastic polyurethane composites (a), EMI shielding model for multiple layered composite assembly (b), reflection of electromegnatic waves from MXene sheets (c), reactive functional groups present on MXene sheets on fiber surface (d), foldable and stretchable highly flexible fabric coated with MXene for EMI and Microwave shielding via thermal treatment(e & f). Reproduced with copyright materials. Elesivier, 2022 (Duan et al., 2022).

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The study shows that, facile fabrication method for the preparation of the composites had an excellent EMI shielding material, which may easily reached with greater number of possibilities in intelligent wear and electronic systems. The MXene based as a framework limits the growth of PPy, precludes the re-stacking of PPy, and endorses the operational steadiness of Ti₃C₂/PPy nanocomposite (Liao, 2022; Wang, 2019). Furthermore, the intersegment of reliable PPy particles increases the interlayer space MXene sheets itself, and the exceedingly accompanying with polymeric restriction, which can deliver supplementary trails for electrolyte ions dispersal and charge distribution. Therefore by aggregation of developed assemblies explicate EMI-SE and may reduce the charge transmission confrontation is managed. Most of all it has exposed as a low-cost and a suitable way to construct such structures on large-scale made up of MXene/PPy nanocomposites films and requires excessive impedance matching and auspicious forecasts as conductor constituents for super capacitors (Xu, 2019).

The development of different material assemblies for restriction of EMI is great concern of the developing society in recent years, which requires more attention of the scientific community to reduce such pollution; with the recent developments of research in the field of science and technology. In order, to resolve these complex problems of EMW absorbing over a variable bandwidth and environmental protection with oxidation and reduction which is resistant other than traditional single phase nickel spheres and MXene based composites exhibited the remarkable ferromagnetic attributes as presented in Fig. 39 (a-e); showing double-loss including dielectric and magnetic loss and is considered as an efficient EM absorbing materials (Shi et al., 2021; Fan, 2020). The resultant MXene-based aerogel pooled with the well retained essential construction of MXene and aligned core–shell structure shows promising electrical conductivity of 1085 S cm⁻¹. When used as conductive networks in shielding materials, the aerogel made by mixing the epoxy nanocomposite; also demonstrated with remarkable electrical conductivity of 695.9 S m⁻¹. Whereas, the EMI shielding effectiveness of the nanocomposite exceeded to 50 dB with a determined value of 56.4 dB over X-band. The developement of 3-D MXene-based architecture releases a innovative path for the use of MXene in various arenas. Though, the re-stacking problem still exists in these materials, which can significantly decrease their EMI-SE performance; and can be optimized with increasing thickness and mass loading (Yin, 2020).

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Fig. 39

SEM image of MXene loaded Nickle micro-spheres (a), EMI response of developed MXene@Ni-based composite (b), reflection loss (R_L) response of comoposite (c), chemical exfoliation of MXene and in-situ loading of Ni-Particles via hydrothermal (d), and layered MXene sheets laoded with Ni-Spheres in between design model for Microwave and EMI sheilding(e), reproduced with copy right material @ Royal Society of Chemistry, 2021 (Deng et al., 2021).

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3.2.4 MXene-rGO/polymer-based nanocomposites

The MXene modified with poly dopamine (Ti₃C₂Tx/PDA) composite film electrode was reasonably intended and effectively produced by one-step in situ polymerization. The as modified films with dopamine developed an opposite charge on the surface of films coated nano fibers, films and sheets (Wu, 2020). Similarly another work is proposed to investigate the conductive polymer (PEDOT) as a spacer between the MXene sheets and graphene sheets to avoid the agglomerations. In which the 2-D materials are incorporated and employed as 3D architecture of a aerogel to restrict the restacking of 2-D MX nanosheets without the use of additives; which exhibited an improved performance as compared to untreated ones MX-rGO films for EMI shielding and MA absorption in operational manner (Han, 2019). The MXene modified with poly dopamine (Ti₃C₂Tx/PDA) compound electrodes were effectively produced by in-situ polymerization reasonably used for MA nand EMI shielding. The PDA modified films developed opposite charge on the surface of the Ti₃C₂Tx films coated nano fibers, films and sheets as preceded in Fig. 40 (a–f) (Huan, 2022; Rajavel, 2020; Bian et al., 2019).

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Fig. 40

Digital image for the chemical etching and Fabrication of MXene-HEC films (a), MXene-HEC composites films foldeable (b), SEM images showing crossectional view of composite films (c), EMI Sheilding response of developed composite films with different thickness (d), EMI SE of M−Ti₃C₂T_x/HEC composite film at different stacking thicknesses (e), and an average A, R and T of M−Ti₃C₂T_x/HEC composite film at different stacking thicknesses (f), reproduced with copyright materials, Springer an open access 2021 (He et al., 2021).

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The 3-D MX-CNTs aerogel films were developed by using a vacuum filtration and freeze-drying process. The results show that the carbon nanotubes into the MXene-based aerogel can prevent the restaging of MXene nanosheets with each other due to the Van-der Waals forces, and lead to three-dimensional interconnected porous structure with large specific surface area and excellent compressive recovery (Ryu, 2022). However, it is anticipated to consistently anchor a hydrous ruthenium oxide (RuO₂·xH₂O) nanoparticles on MXene nanosheets. The resulting RuO₂@MXene composites loaded with silver nanowires (AgNWs) to ultimately assist as a printed textile electrode on micro-scale for the high-performance shielding effectiveness. Furthermore, the performance of the nanocomposite was dependent on thickness and diffusion mechanism with different types of hydrated ions by combining the experimental and DFT results. Owing to higher electrical conductivity, MXene@PS heterogeneous structure of micro-meter thickness shows an excellent EMI-SE with foremost absorption contribution in the microwave frequency range of (X-band) (Zhang et al., 2021). The total shielding efficiency along with EM waves’ absorption capability of the composite films were optimized by different beads sizes of polymers(PS). Composite films with smaller beads size possessing a higher dielectric domain density due to the larger surface area and revealed better EMI shielding performance (Zhan, 2021).

Even though electrically conductive polymer compounds (ECPCs) are considered as an auspicious material in the solicitation of EMI shielding, however to endow the ECPCs for multifunctional use is a great challenge. Here an innovative polyurethane/polydopamine/silver nanoparticle (PU/PDA/Ag) sponges were developed with outstanding protection against EMI shielding. The complex assembly was magnificently conceived by a facile technique and acquired by two fold processing:

1. Polydopamine (PDA) was decorated on the surface of PU exfoliators with dopamine coated self-polymerization as demonstrated in Fig. 41 (a & b).

2. Ag nanoparticles were in-situ grown on the surface of PU sponges by electroless plating.

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Fig. 41

Development of PU-modified with Polydopamine PDA via hydrothermal reduction foams extended image size of pure PU after loading with Ag (a & b), simulation of microwave absorption under IR rendering of developed foam (c), and sensory and body movement response (d). The Figure has been reproduced with copyright permission from Elsevier, 2020 (Liang et al., 2020).

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The developed sponge like structure showed a maximum EMI-SE of 84.6 dB with the consistent SE response with an unconditional SE value of 2625 dB cm³ g⁻¹ and 5250 dB cm² g⁻¹. These results are much higher as compared to the other shielding foams and sponges. Meanwhile, the developed sponge retained as little thermal conductivity of (52.72 mW/mK) but exceptional compression resilience and piezoresistive properties as demonstrated in Fig. 41 (c & d) (Zhan, 2021; Zhang et al., 2021). In addition, the chemical and electrochemical stability of MXene electrodes was achieved through unconventional assembly methods. These highly conductive polymers are also extensively used for EMI and MA purposes with improved electrical, thermal, mechanical and electronic properties of the MXene-rGO nanocomposites for effective EMI, shielding, and supercapacitors applications (Sambyal, 2019). Whereas, the fabrication of a free-standing porous substrate as a 3D network of graphene and MXene, may have weak inter-sheet interfaces due to more gapes or vacuoles; which can trap and entangle the electromagnetic waves. Nevertheless, the higher interfacial polarization may be increased for the constructed assembly from the lightweight 3D porous structure through bridging the MXene films with polyamide(PDA) structure on macro-molecules (Liang et al., 2020). These outstanding performance and higher flexibility with improved electrical conductivity makes these aerogels; as a new class of materials and favorable applicant for restraining the EMS. More interestingly, more improvements in MA performance and EMI shielding can be attained with a maximum reflection loss (R_L) value of − 45.4 dB at 9.59 GHz and an operational (MA) fascination bandwidth (<−10 dB) of 5.1 GHz were attained with greater sensitivity and long-term stability under variable working conditions.

In addition, the thermal insulation and SE performances stability against the heat of the porous MXene/PI aerogel were also explored. Thus, the novel techniques may also provide a new dimensions are concerns for the design and development of new 3D highly porous MXene based assemblies and would expand significantly the potential applications of MXene materials. Furthermore, Ti₃C₂Tx/CNF composite paper is a highly flexible, which can withstand variable loading, and even under folded into complex shapes; which exhibits a negligible loss of electrical conductivity after repeated folding/unfolding process. The Ti₃C₂Tx/CNF nanocomposite shows better performance towards microwave and EMI shielding effectiveness. The results also demonstrate that the Ti₃C₂Tx/CNF composite paper is a promising candidate for the presentations of bendable, portable and e-textile devices (Liang et al., 2020; Geng, 2019). Similiarly in another work, an anisotropic composite of a sponge like structure containing of (CNFs) and chemically reduced silver nanowires over ferric oxide (AgNW)@Fe₃O₄ were in-situ synthesized. The developed composites showed an improved (SE) performance due to the addition of anisotropic materials in the composites, which resulted as synergistic effect among CNFs, AgNWs, and Fe₃O₄. The sponge showed a low density (16.76 mg/cm³), better saturation magnetization of (4.21 emu/g) with an conductivity (0.02 S/cm), and anisotropic EMI shielding capability by varying the ratios of (1:0.3) among AgNWs and Fe₃O₄ with a loading of (0.15 vol%) in the sponge. The reflection loss (R_L) of the sponge with the an improved interface polarization and impedance mismatch reached around 2.3 dB, and resulting 7.2 % improvement of the total reflection loss (Zhang, 2020). In another work; researcher investigated the properties of hybrid materials consisting of MXeene and PEDOT: PSS nanocomposites with graphene and silver nanowires for microwave and EMI shielding effectiveness. However several (ICPs) polymers are generally applied on wearable fibrous assemblies for mass-scale production of such fabrics and films coating to enhance the EMI and MA shielding performances. The shielding performance and electrical properties of the developed nanocomposites were improved made of the conducting polymer; after coating on the textile fabric and are greatly influenced by various parameters; including the weight, deposition level and fabric or composite; thickness of the polymer coating layer, the thickness of the fabric, nature and type of the substrate, its surface functionality, and chemical or physical binding strength on the surface of the textile substrate (Chen, et al., 2022). The study showed an improved performance as compared to the pure MXene and graphene. The shielding effectiveness and MA performance were greatly influenced by the addition of conductive polymers i.e PEDOT: PSS, MXene/PPy and PANi nanohybrids, which exhibited an enhanced shielding performance as compared to pristine ones. The hybrid structures of conductive polymers with graphene and MXene showed the highest response towards MA and EMI shielding with a maximum efficiency of 99.9 % absorption at temperature and the highest EMI shielding effectiveness was attained. Similarly MXene and rGO with PANi and PPy AgNWS; showing a synergistic effect of conductive polymers with rGO and Ti₃C₂Tx MXene sheets with higher electrical conductivity due to the conductive paths (Cheng, 2020). However, the highest selective shielding range of the developed nanocomposites was attained by the MXene, PEDOT: PSS, rGO-PANi, and MXene-rGO/AgNWS ternary structures respectively with conductive polymer a shielding layer. Previous studies made on MA over a variable bandwidth of 2–20 GHz for paraffin-MXene and ferric oxide (Ti₃C₂Tx)/Fe₃O₄ coated MXene composites. The electromagnetic characterization of such developed composites was carried out in the broad frequency range (2–18 GHz) using a CST-microwave. The simulated result indicates that the solitary coating of MXene complexes exhibits an outstanding reflection loss (R_L), −30 dB, however, bandwidth is very narrow even if increasing the thickness to 8 mm, which was well matched with experimental data (Hu et al., 2020).

The results demonstrate that the conductive polymers would open new opportunities for exploring more MXene and graphene-based nanocomposites with controlled composition and morphologies towards higher MA and EMI shielding performance. The designed a macro-scopic pyramidical configuration succeeding in an excellent R_L bandwidth at a certain configuration, which is due to the higher interfacial impedance matching. This shows that the importance of the structural design of MXene containing polymer nanocomposites for real-time applications such as military communication. Generally, the graphene and 2D materials are widely used to develop solgel and hydrogels using freeze-drying techniques. As other chemical reduction and thermal reduction techniques also be used to reduce the interaction of thesheets with eachother and restacking of graphene sheets (Sambyal, 2019). Therefore, the most widely used and preferred technique is freeze-drying, in which water content is evaporated at the lowest temperature of −48–50 °C to keep separate sheets with ice flakes to keep apart sheets from each other and avoid any re-binding of oxidized GO sheets, and can easily be dissolved in different solvents and even in water-based solution, as presented in Fig. 42 (a-c). The effect of cell size can be studied over a broader extent with variable loading of MXene on the electrical conductivity (σ), EMI effectiveness, SE values, mechanical, and thermal properties. Similarly, the designed rGMH/epoxy nanocomposites were evaluated and conversed (Sambyal, 2019; Wang, 2019). Herein, the work also validated and well-organized method for the fabrication exceedingly the conductive 3-D MXene films and porous constructions made up of GO. The structure was desiccated by vacuum assisted filtration and a hydrothermal reduction followed by freeze-drying method (Yin et al., 2020). The developed nanocomposites aerogel may comprise a highly aligned and more oriented micro-structure (wall-brick like) in which graphene work as core skelton, whereas the tightly packed MXene (Ti₃C₂Tx) sheets work as a shell of the walls of the structure as presented in Fig. 42 (d-f). The resultant nacre like structure could facilitate in higher attenuating of microwave and electromagnetic waves due to its highly porous and conductive infrastructures (up to 1085 S cm⁻¹).

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Fig. 42

Chemical etching of MXene for the development of few layered sheets of MXene and MXene/WPC based composite's fabrics (a), composites hydrogel films like brick-wall mortar like SEM image of aerogels (b), MXene aerogel with WPC as flame retardant foam (c), light weight foam standing (d), model design mortar brick structure (e), thermal insulation performance of aerogel microwave assisted thermal reduction of nanocomposites films (f) for microwave and EMI shielding. Reproduced with the copyright permission by Elsevier 2020 (Liang et al., 2020).

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This highly efficient performance and conductivity are endowing to stable epoxy interference in the nanocomposite; with an electrical conductivity of 695.9 S m⁻¹ and an EMI-SE) values greater than 50 dB in the X-band by using very minimum content percent of rGO and MXene sheets with the content of 0.74 vol%. The presented work concludes; that the results are best for epoxy nanocomposites as compared to other polymer type nanocomposites over the same loadings of MXene reported in previous works (Liu et al., 2019). The natural cotton fibers dispersed in the sucrose aqueous solution and was consolidated by means of pressure filtration, drying, and carbonization techniques, to prepare heat-insulating and fire-resistant carbon composite foam. When the sucrose concentration is higher than 200 g/L, the carbon syntactic foam undergoes a partial flexible to rigid transition. Tubular carbon fibers were formed from cotton and were welded by sucrose-generated amorphous carbon at their contact points, resulting in low sucrose concentrations. The lower part is pliable, and the advancement of the fiber-to-fiber bonding area was attained at high sucrose concentrations and resulted in formation of a rigid foam. The interfere spaces and porosity in the lumen of carbonized cotton fibers resultes in low thermal conductivity. The developed nanocomposite fiber assemblies may be considered as potential candidates for MA and EMI SE due to their very thin structure, which can be used in multiple layered composites for effective shielding performance (Jia et al., 2020). The work as previously reported on the fabrication and coating of different intrinsic conductive polymers i.e Pyrole, and PPy based aerogels, which does not significantly change the mechanical performance but allows the development of highly flexible, stretchable and bendable conductive textile substrates with enhanced EMI shielding performance as shown in Fig. 43 (a & b).

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Fig. 43

Developed MXene and pyrrole coated fabrics with PPy/MXene composites and  knitted fabric coated with MXene ( a & b), Shielding response of fabric (c), Electrical conductivity of MXene based composites (d), Stability of EMI shielding by effects of water resistant,  (e) Air permeability of synthesized materials. Reproduced with copyright material by John Wiley and Sons, 2021 (Wang et al., 2019).

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Whereas, the performance of textiles substrates coated with MXene can also be improved with the number of coating layers on the fiber structures such as woven, and non-woven fabrics as shown in Fig. 43 (c-f) (Qing et al., 2016).The commercially available fabrics and laminates are produced with different materials on textile fibers; which exhibits higher SE and satisfactory performance with isotropic behavior. Interestingly, previously reported materials were prepared by using ultra-light Ni/MXene/rGO (NiMR-H) aerogels with EAB of 6.45 mg cm⁻³ and provides the highest MA performance for MXene-based absorbing materials with a minimum reflection loss of (R_Lmin) value of − 75.2 dB and higher (ES) percentage of (99.9 %) for microwave over a broadest EAB range of 5.0–7.3 GHz (Feng et al., 2018).