View PDF VersionPrevious ArticleNext Article
 
DOI: 10.1039/D1QM00659B (Review Article) Mater. Chem. Front., 2021, 5, 6444-6460

Tailorable MOF architectures for high-efficiency electromagnetic functions

Si-Qi Zhu , Jin-Cheng Shu and Mao-Sheng Cao *
School of Materials Science and Engineering, Beijing Institute of Technology, Beijing 100081, China. E-mail: caomaosheng@bit.edu.cn

Received 30th April 2021 , Accepted 7th July 2021

First published on 16th July 2021

Abstract

The advent of 5G and 6G eras switches on intelligent life and information revolution. Unfortunately, the resulting electromagnetic radiation would harm human health and current automation systems. Hence, the worldwide demand for novel and efficient electromagnetic functional materials has been growing dramatically. Metal–organic frameworks (MOFs), which possess diverse structures and components, have inspired infinite passion and creativity of researchers in the electromagnetic field. Herein, the recent progress in synthesis of MOF architectures is discussed. Then, the attenuation mechanism of electromagnetic waves inside MOF architectures is revealed, and the development of highly efficient MOF-based microwave absorption and shielding materials with tunable electromagnetic properties is presented. Finally, the current challenges and possible future research directions are dissected, which provides guidance for fabricating MOF-based electromagnetic functional materials.

image file: d1qm00659b-p1.tif

Si-Qi Zhu

Si-Qi Zhu received her BS degree from Wuhan University of Technology in 2015. She is currently pursuing MA degree in Beijing Institute of Technology. Her current research interest is MOF-based functional materials and devices.

image file: d1qm00659b-p2.tif

Jin-Cheng Shu

Jin-Cheng Shu received his BS degree from Beijing Institute of Technology in 2018. He is working towards PhD degree at Beijing Institute of Technology. His current research interest includes advanced functional materials and devices.

image file: d1qm00659b-p3.tif

Mao-Sheng Cao

Mao-Sheng Cao received his MS and PhD degrees from Harbin Institute of Technology in 1989 and 1998, respectively. He is currently a distinguished professor of Beijing Institute of Technology. His current research interest includes low-dimensional electromagnetic functional materials and devices.

1. Introduction

The coming of the 5G and 6G eras will trigger a huge technological revolution, and bring unlimited opportunities to the society.1–4 However, the undesirable electromagnetic radiation leads to adverse impacts on human health and normal operation of sensitive electronic apparatus.5–12 Therefore, the fabrication of novel microwave absorption and electromagnetic interference (EMI) shielding materials offers a promising way to solve the hot issue in modern life.13–21

MOFs have received a lot of attention due to their tunable chemical composition, porous structure, extremely high specific surface area and diverse properties.22–27 The wide selection of metal and organic ligands provide MOFs with almost unlimited tunability in terms of composition, structure and performance diversity, which offers great potential in the fields of gas separation, energy storage, sensing and catalysis.26–30 However, the poor stability of many MOFs in water or other harsh conditions has considerably limited their further application and commercialization.31,32

Recently, MOFs have been demonstrated as suitable precursors for decomposition and carbonization to yield carbonization derivatives with high thermal and chemical stability, which presents an outstanding advantage in the electromagnetic field.33,34 The derivatives exhibit light weight, high dielectric constant and even magnetic properties.35 Moreover, the derivatives can inherit the intrinsic framework structure and component from their parent MOF. The structure-dependent advantages such as the large surface area and uniform pore distribution can produce rich interfacial genes, expand conductive networks, and cause strong multiple scattering and reflection of electromagnetic waves.36–38 In particular, the assembly of MOFs into hierarchical superstructures may further enhance the electromagnetic performance.39 Designing complex MOF-based materials on different levels offers an effective platform for optimizing the electromagnetic response and energy conversion.40–42 Therefore, the delicate and rational design of MOF architectures may endow the material with tunable properties, and achieve highly efficient microwave absorption and EMI shielding (Fig. 1).


image file: d1qm00659b-f1.tif
Fig. 1 Tailoring the MOF architectures for microwave absorption and EMI shielding. Reproduced from ref. 50, 69, 75, 88, 90, 96, 104, 105 and 108 with permission. Copyright 2019, Elsevier; Copyright 2016, Wiley-VCH; Copyright 2020, Elsevier; Copyright 2019, ACS; Copyright 2019, ACS; Copyright 2019, Elsevier; Copyright 2020, Elsevier; Copyright 2020, Elsevier; Copyright 2020, ACS.

In this review, we provide a comprehensive review of recent development and the synthesis strategies of MOF-based complex nanostructures and hierarchical superstructures, and extensively discuss the effects of micro/nano-structures on electromagnetic energy dissipation. Then, we highlight the developing situation of MOF-based materials in the electromagnetic field and investigate the electromagnetic loss and energy conversion inside MOF architectures. Finally, we propose the challenges and opportunities faced by MOF-derived materials for microwave absorption and EMI shielding.

2. Synthesis of MOF-derived architectures

Since the property of MOFs is largely affected by their structure, composition and preparation methods, diverse MOF particles with novel structures have been reported.41–44 In addition, MOF particles with a definite size and morphology can spontaneously assemble into more complex superstructures driven by particle interaction.39,40 The complex MOF architecture could integrate the chemical properties of components and unique structural characteristics to achieve high attenuation ability.1,12,16,18,33,36–38 According to their structures, the controllable MOF architecture tailoring is discussed extensively in this section.

2.1. MOF-derived nanoparticles with complex structures

2.1.1 Hollow structures. Hollow materials are a significant kind of advanced material that displays some desirable properties owing to their low density, high specific surface area and rich reactive sites.44 The construction of hollow structures can provide abundant interfaces and enhance the multi-scattering, exhibiting optimal electromagnetic properties.45 The large volume shrinkage usually occurs when MOFs are converted to inorganic materials, which can be used to create hollow metal/carbon-based nanostructures.43 In general, many MOF derivatives with hollow structures have been reported via various fabrication strategies such as heat treatment, template-assisted strategies, acid etching approaches and ion exchange reaction under appropriate conditions.

The template-assisted strategy is a common method to build the hollow structure of the MOF. In particular, the carbonized derivatives with hollow structures can be prepared by selecting some hybrid materials with low stability as templates due to the decomposition of the hybrid compounds at high temperature. For instance, Li and co-workers reported the synthesis of N,Fe-codoped hollow porous carbon by in situ growth of an Fe-doped ZIF-67 shell onto the surface of polystyrene nanoparticles, followed by carbonization treatment.46 The polystyrene sphere serves as a soft template to anchor metal ions and nanocrystals and subsequently decomposes to provide hollow structures.

The construction of hollow structures by acid etching has also been reported. Acids can release free protons, which are mostly confined in the center of the MOF crystal, to break the framework of the MOF. Finally, hollow MOF crystals with inherent crystal frames can be obtained. Li et al. prepared the Ag-doped ZIF-derived porous carbon nanocubes with a hollow structure via an in situ tannic acid (TA) etching/reduction strategy.47 The as-prepared ZIF-8 is dispersed in anhydrous ethanol and mixed with TA solution, and TA firstly covers the surface of ZIF-8 and then releases protons to etch the inner region of ZIF-8 to obtain hollow nanocubes. In addition, the attached TA can protect the framework of ZIF-8, while the obtained HZIF-8 still maintains the cubic hexahedral structure.

However, these synthetic methods are tedious owing to the removal of the templates by etching or calcination. Cation exchange may be utilized to simplify the preparation of unique hollow structures. Liu et al. recently reported hollow Mn+-PA micropolyhedra via cation-exchange synthesis. The exchange of the incoming Mn+ and parent Co2+ ions results in hollow micropolyhedra.48

2.1.2. Core–shell structures. In addition to the hollow structure, MOFs can be further improved and extended by incorporating other functional species to form more complex structures. In particular, core–shell MOFs are one of the most important members of the multifunctional MOF family. They are composed of an inner core material surrounded by a shell material, where the MOF material can be used as a core or shell. The integration of optimized composition and morphology endows the core–shell material with highly unique functions that can be used as a good microwave absorber.5,6

Various methods have been developed for the construction of core–shell MOF materials. One is to use heterogeneous materials as templates to grow MOF monomers. Owing to the supply of Zn2+ from dissolved ZnO in solution, Feng and co-workers grew ZIF-8 on the outer layer of ZnO colloidal microspheres.49 Then the as-prepared ZnO@ZIF-8 is heated to 500 °C under argon flow to construct carbon-coated ZnO core–shell microspheres.

The second is to grow hybrids on the MOF molecular template. Zhang et al. reported the fabrication of yolk–shell nanoreactors by the direct nitridation of MOF@SiO2 precursor.50 The MOF yolk employs active sites to grow the octahedral SiO2 shell, and the inner core is converted into broken particles after annealing under a nitrogen atmosphere (Fig. 2a–d).


image file: d1qm00659b-f2.tif
Fig. 2 (a) Schematic illustration of the fabrication procedure of the yolk–shell CoN/N-C@SiO2, and (b–d) TEM images of CoN/N-C@SiO2-500. Reproduced from ref. 50 with permission. Copyright 2019, Elsevier. (e) Schematic illustration of the synthesis of hollow yolk–shell Co@C-N, and (f–h) SEM and TEM images of Co@C-N(1)-800. Reproduced from ref. 51 with permission. Copyright 2018, ACS.

In addition, different kinds of ZIFs can also be integrated into core–shell structures. Chen et al. grew ZIF-8 on the surface of ZIF-67 to synthesize hollow Zn/Co-ZIF via hydrothermal treatment.51 After the pyrolysis process, the composite is obtained with the Co doped C–N nanosheet as the core and the porous N-doped graphite carbon as the shell, as shown in Fig. 2e and f.

2.1.3. Multi-shelled structures. The multi-shelled structure is an assembly of multiple shells with voids between the individual shells. It can not only inherit the advantages of the single shell structure, but also show the superiority of unique shell structure and complex composition.52 The multi-shelled structure has gained extensive interest in many fields due to its extremely high surface area, abundant active sites, high loading capacity and buffering effect.41 Simultaneously, this structure can also contribute to multiple scattering and form a conductive network to enhance the attenuation of electromagnetic waves.

A number of inspiring works have been reported. For example, Chen et al. demonstrated a universal strategy for multi-shelled hollow microspheres of transition metal oxides.53 During the pyrolysis process, the surface temperature of spherical Ni-MOF and Co-MOF is higher and the surface is decomposed into porous carbon first to form the initial shell. With the extension of pyrolysis time, the second layer and the third layer are gradually formed in the pyrolysis process.

More layers and more complex structures have also been reported. Qiao and co-workers first reported the design of multi-shell Sb2S3 structures obtained from MOF templates.54 In the initial sulfidation process, the ZnS shell forms on the surface of ZIF-8. Then, the inner core shrinks and the new surface of the inner core ZIF-8 is exposed, forming a yolk–shell structure ZIF-8@ZnS during the quenching process. After three quenching and sulfidation processes, the multi-shell structured Sb2S3 microparticles can be achieved.

2.1.4. Nanoframe structures. Benefitting from their structural merits including large surface areas, added internal volume, and good structural stability, nanoframe architectures are also very attractive. These internal or external surfaces promote intense scattering and reflection of electromagnetic waves, which increases energy dissipation. At the same time, the robust structure of nanoframes is also conducive to their use as a sacrificial template for the synthesis of carbonized derivatives with new morphologies through the calcination approach.55 Avci et al. developed an anisotropic wet etching approach to prepare nanoframe structure ZIF-8 and ZIF-67, using XO/HCl (pH 2.5) as an etchant solution.56 The acidified XO can break the coordination bond between the metal ion/cluster and the organic connective group, giving priority to etching the specific external crystal surface. The etched ZIF-8 and ZIF-67 microboxes possess four openings and thin walls. It is worth mentioning that the etched morphologies can be tuned by simply adjusting the pH of the etchant solution. In a follow-up study, Jeoung et al. presented a synthesis of adamantane-shaped carbon nanoframes through combining selective etching and pseudomorphic thermal conversion of ZIF crystals.55

In addition to the ZIF material, Ni–Co Prussian blue analogue (PBA) nanocubes can also be etched into NiS nanoframes with tunable sizes. Lou et al. reported a structure-induced anisotropic chemical etching/anion exchange method to prepare Ni–Co PBA cubic nanoframes.57 Unlike ZIF-8 or ZIF-67, the edges of the nanocubes are partially etched and exchanged with S2− ions to form a cubic skeleton, while the center of the nanocubes completely dissolved (Fig. 3a–e). Chen's group reported another novel Co–Co PBA nanoframe via a facile strategy with precipitation, chemical etching, and low-temperature phosphidation.58 In this structure, a nanocube is initially etched at its corner, and the obtained nanoframe exhibits eight corners of an open structure with a hollow interior space.


image file: d1qm00659b-f3.tif
Fig. 3 (a) Schematic illustration of the formation process of NiS nanoframes, and FESEM images of the products obtained after reaction for (b) 0 h, (c) 0.5 h, (d) 2 h, and (e) 6 h. Reproduced from ref. 57 with permission. Copyright 2015, Wiley-VCH.
2.1.5. Nanoplate structures. Surfactants such as cetyltrimethylammonium bromide (CTAB) have been widely used in recent years to control the morphology and size of MOFs. Previous studies have shown that the strong interaction between surfactants and nanocrystals plays an important role in the crystal growth rate. For example, Lou et al. reported the novel synthesis of ZIF-67 nanoplates through a surfactant assisted hydrothermal reaction.59 These ZIF-67 NPs are uniform with an average side length of about 900 nm and thickness of about 160 nm. In a related work, Zhang et al. demonstrated a microwave method to prepare HZIF-W.60 A polyhedron formed by 3D transition metals and 2-methylimidazole is linked to WO42− units, forming the nanoplates. A shape of square nanoflakes can be observed and these nanoflakes have a lateral length of 200 nm and a thickness of 30 nm on average.

In addition, a unique dodecagon nanoplate structure had been successfully prepared by Riley and co-workers via an ammonia-assisted in situ cation-exchange method.61 In the procedure, the precursor NiCo–PBA reacts with ammonia to achieve a nanoframe intermediate, which is the result of selective chemical etching by ammonia. Afterward, the nanoframe can be transformed into Pd-e-NiCo-PBA with a dodecagon structure via an in situ cation-exchange process of palladium with nickel.

2.1.6. Other complex structures. In addition to the conventional MOF structures mentioned above, other nanostructures with special morphologies have also been reported. Unique mesoporous copper cobalt sulfide crumpled nanoflowers had been successfully prepared by Zhao and co-workers through simple reflux and solvothermal reactions using the ZIF-67 as a sacrificial template.62 The released Co2+ ions from ZIF-67 are partially oxidized to Co3+ and form Cu–Co–ZIF precursor by co-precipitation with Cu2+. Then, the CuCo2S4 with a hierarchical crumpled nanoflower structure is obtained via sulfurization treatment. Significantly, this strategy is also suitable for the synthesis of Mn–Co sulfide nanoparticles.

Based on the previous research, Lou and co-workers investigated the effect of defects in the Ni–Co Prussian-blue-analog on etching behavior. After treatment with an appropriate amount of ammonia solution, the interior defect-rich parts of Ni–Co PBA would be etched at a faster rate, leading to the formation of a cubic cage structure consisting of six pyramid-like walls.63 In a follow-up study, single-holed Co/NC hollow particles were controllably synthesized by Lou and co-workers.64 PS spheres serving as functional particles can also be encapsulated inside the ZIF-67 shells to form multifunctional composite materials. During the carbonation process, the strong hydrocarbon gas outflux generated from the thermal decomposition of the PS template leads to the formation of a large through-hole on the surface of the Co/NC hollow particles. The unique single-holed hollow structure with the large cavity may provide a new way to fabricate great microwave absorbers with a controlled morphology.

2.2. Assembly of MOFs into hierarchical superstructures

In addition to delicate design of the nanoarchitecture MOFs or their composites, MOF nanocrystals can also be used as building units to fabricate hierarchical superstructures. In this architecture, different levels of hierarchical superstructures can be easily observed. The MOF particles, as the primary architecture, gather to form a specific morphology as the secondary architecture. Assembling these nano-sized crystal MOFs with unique sizes and morphologies might offer broad possibilities for the synthesis of multifunctional materials, instead of changing their composition.65
2.2.1. 0D hierarchical superstructures. Hollow 0D hierarchical structures are a common form of superstructure, which consists of dual hollow scaffolds: a macrohollow in the core and cavities in the shell. In general, one of the possible methods to construct hierarchical hollow structures is using solid templates or self-sacrificing templates to assemble MOFs. The large internal cavity is formed by a diffusion-controlled process or removing the templates.39 With further processes, the MOF crystals are transformed into hollow spheres or polyhedra and form the outer shells.

For example, Lou's group fabricated CdS hierarchical multi-cavity hollow particles; the high catalytic activity of CdS is ascribed to abundant active sites and enhanced light scattering because of the unusual hollow structure.66 Another noteworthy example of assembling MOFs into hollow structures was demonstrated by template-free formation. Seo et al. developed a facile approach to prepare “brain-coral-like” CoS2@N-doped graphitic carbon nanoshells.67 The primary ZIF-67 spheres built up a 600 nm hollow structure (Fig. 4a–e).


image file: d1qm00659b-f4.tif
Fig. 4 (a) Scheme of the synthetic procedure of the mesoporous hollow CoS2@NGCNs, and SEM images of (b) ZIF-67 hollow-spheres, (c) Co@NGCNs, (d) Co/CoS2@NGCNs, and (e) CoS2@NGCNs. Reproduced from ref. 67 with permission. Copyright 2019, Wiley-VCH. (f) Schematic illustration of the construction of the hydrangea-like superstructure. Reproduced from ref. 68 with permission. Copyright 2019 Wiley-VCH.

For the first time, a hydrangea-like superstructure of open carbon cages was reported by Xu and co-workers via a self-template strategy.68 The guest Fe ions are introduced into the core–shell Zn@Co-MOF precursor to catalyze the growth of carbon nanotubes in the subsequent calcination process. Finally, the open-wall carbon cages are connected through nanotubes to form a hydrangea-like superstructure (Fig. 4f).

2.2.2. 1D hierarchical superstructures. Abundant templates such as nanorods or nanofibers will allow the assembly of MOF subunits to form other unusual 1D hierarchical architectures. The template can promote the heterogeneous nucleation process and direct the growth of MOF crystals in the desired direction.39 Polyacrylonitrile (PAN) nanofibers can be used as templates to construct the hierarchical CNT/Co3O4 microtubes.69 Co(Ac)2 can be uniformly distributed in the PAN nanofibers to provide the cobalt source for the growth of ZIF-67. Afterward, Co nanoparticles are first yielded and further catalyze the growth of CNTs from carbon precursor via the heat treatment, leading to the formation of the hierarchical hybrids (Fig. 5a). Analogously, cobalt acetate hydroxide nanoprisms could be applied as the self-engaged templates to grow ZIF-67 particles (Fig. 5b).70
image file: d1qm00659b-f5.tif
Fig. 5 (a) Formation of the hierarchical CNT/Co3O4 microtubes. Reproduced from ref. 69 with permission. Copyright 2016, Wiley-VCH. (b) Schematic illustration of the formation of CoS2 hollow prisms. Reproduced from ref. 70 with permission. Copyright 2016, Wiley-VCH. (c) The illustration of the synthetic process of Co-LDH/SCF microtubes. Reproduced from ref. 71 with permission. Copyright 2020, Elsevier.

Other templates or carriers provide further feasibility of assembling MOF particles into superstructures. Wu et al. used activated short carbon fibers (SCF) as a carrier to produce hierarchical Co3O4/SCF composites (Fig. 5c).71 In addition, Sun and co-workers demonstrated a template-engaged crystal self-assembly method to produce hollow structures composed of nanosized ZIF-67 single crystals.72 The ZIF-67 grew on the surface of the urchin-like CCH precursor and assembled into the wall of hollow tubules during subsequent carbonization.

2.2.3. 2D hierarchical superstructures. To date, an alarming number of studies on MOF films or patterned synthesis have highlighted the importance of this field. The 2D hierarchical superstructures derived from MOFs are expected to offer unique opportunities with a potential to achieve superior performance. Qiu et al. demonstrated the formation of a homochiral MOF membrane on a nickel net via a single metal source method.73 The nickel net not only acts as a substrate to support 2D hierarchical superstructures, but also provides the nickel source to form the crystal film, which was defect-free and packed densely 20–30 μm crystallites.

A novel, versatile pen-type lithography-based methodology was developed to control the growth of HKUST-1 crystals on surfaces by Maspoch and co-workers.74 Droplets containing a solution of Cu(II) ions and trimesic acid (H3btc) can form HKUST-115 single crystals onto surface-modified gold substrates by direct-write FEMTO. It is likely that this approach can be generalized to control the growth of many MOFs at the single-crystal level on several surfaces. Nonetheless, the controllable assembly of MOF-based 2D hierarchical structures still remains challenging and requires more distinct synthetic strategies.

2.2.4. 3D hierarchical superstructures. The formation of MOF assembled 3D network structures with continuous and extended systems usually requires the combination of other materials, such as carbon fibers, graphene or 3D porous carbon networks, for structural support to maintain the hierarchical architecture.39,40 In addition to the micropores that stemmed from the MOF itself, the 3D hierarchical structure has higher porosity. The introduced materials not only restrict the growth and aggregation of MOFs, but also participate in the formation of conductive networks and porous structures with large surface areas, providing more active sites for reflection and scattering of microwaves, effectively adjust the electromagnetic parameters and improve the impedance matching.39 For example, cotton fiber exhibits a natural micron-sized hollow fibrous structure, which makes it a perfect raw material for fabricating low coat 3D hierarchical materials. Che et al. presented the hierarchical carbon fiber coated with Co/C nano-dodecahedron particles where ZIF-67 particles were in situ grown onto the surface of cotton fibers.75 During annealing, cotton fiber was carbonized into hollow carbon fiber, anchoring the Co/C nano-dodecahedron (Fig. 6a). 3D NPC has also been used to assist MOFs in assembling three-dimensional network structures. The ZIF-67 particles are uniformly anchored into the pores of 3DCN due to the confined effect of 3DCN (Fig. 6b).76 In addition, Tu et al. reported a synthetic strategy to fabricate Co3O4 nanoparticles embedded RGO.77 In the designed strategy, Co-MOF precursors are pyrolyzed to form HoCo3O4/NS-RGO via a two-step calcination process, which is expected to be suitable for the synthesis of other MOF-based hierarchical superstructures (Fig. 6c).
image file: d1qm00659b-f6.tif
Fig. 6 (a) Schematic illustration of the CNT/Co3O4 microtubes. Reproduced from ref. 75 with permission. Copyright 2020, Elsevier. (b) Schematic illustration of the Co3O4@NC/3DCN. Reproduced from ref. 76 with permission. Copyright 2018, Elsevier. (c) Schematic illustration of the HoCo3O4/NS-RGO. Reproduced from ref. 77 with permission. Copyright 2020, ACS.

3. Electromagnetic loss mechanism

The complex MOF architectures could integrate the unique structure and components to provide multiple electromagnetic loss mechanisms, such as conduction loss, relaxation loss, magnetic loss and multi-scattering.45,78 Typically, polarization relaxation processes include interfacial polarization–relaxation and dipole polarization–relaxation. The abundant defects and functional group dipoles in MOF-based derivatives deflect or shift under an alternating electromagnetic field, resulting in strong dipole polarization relaxation.79 In addition, MOF-based derivatives generally inherit the porous structure from their parent MOFs, and provide abundant heterogeneous interfaces. The strong interfacial relaxation could happen to dissipate the incident microwave energy when the carriers accumulated at the interfaces. Cao et al. proposed a capacitor-like model to describe the effect of these microstructures on the attenuation of electromagnetic waves.80 Moreover, the micro-current transport in the MOF-derived carbon causes new conduction loss. Cao et al. put forward the electronic transport modes, the migration and hopping of electrons, and explained them. Compared with other absorbers, carbon-based MOF derivatives possess high conductivity, facilitating strong conductive loss.81,82

In general, the metal ions in MOFs are converted into metals or metal oxides, which improve magnetic loss. In the frequency range of 2–18 GHz, MOF precursors mainly result in eddy current losses, natural exchange (<10 GHz) and exchange resonance (>10 GHz).83 The effect of eddy current loss is inevitable, and it can be reflected by the value of μ′′(μ′)−2f−1. The variable value suggests that the magnetic loss doesn't mainly originate from eddy current loss.16 Furthermore, the complex nanostructure of MOFs causes the multiple scattering and reflection of incident electromagnetic waves. The increased transmission path of the electromagnetic wave enhances the energy dissipation and promotes microwave absorption and EMI shielding.78

4. Application in electromagnetic wave absorption

Thermally stable MOF-based derivatives are considered as a potential ideal electromagnetic function material due to their light weight, high specific surface area and unique porous structure.14,25 In addition, by combining MOFs with other functional materials, such as carbon, semiconductors, foam and so on, composites with a novel microstructure and composition can be precisely designed, achieving optimized impedance to meet the modern requirements of practical applications.

4.1. Co-based absorbers

The poor impedance matching of MOF precursors can be improved by doping and hybridization to achieve a wide absorption band (below −10 dB). For example, a magnetic medium can be introduced into ZIF-67 to achieve excellent electromagnetic attenuation. In 2018, Ji's group synthesized a kind of low-thickness MAM by growing nitrogen doped carbon arrays embedded with Co3O4 nanoparticles on carbon paper.84 The optimal reflection loss (RL) reaches −41.38 and −34.34 dB when the thickness is 2.3 and 1.5 mm, respectively. The NC-Co3O4/CP has a strong microwave response at low thickness, making it possible to use portable and efficient microwave absorption devices (Fig. 7a and b).
image file: d1qm00659b-f7.tif
Fig. 7 (a) Formation process of TA-CP and NC-Co3O4/CP. (b) The plot of RL versus frequency. Reproduced from ref. 84 with permission. Copyright 2018, ACS. (c) Formation process of the MOF/SiC NW hybrid. (d) The plot of RL versus frequency. Reproduced from ref. 85 with permission. Copyright 2017, ACS. (e) Formation process of a hollow cavity in ZIF-67@SiO2-2. (f) The comparison of RL peak values at different thicknesses. Ref. 86 with permission. Copyright 2020, Wiley-VCH.

Silicon carbide nanowires, a kind of highly stable and lightweight one-dimensional nanowire, can be used to fabricate MOF-based hybrids. Xie's group designed a new hybrid nanostructure in which the MOFs are strung together by SiC NWs.85 Compared with pure calcined MOFs, the enlarged aspect ratio and enhanced interface polarization make the MOF/SiC NW hybrids show significantly enhanced EMA capability (−47 dB at 9.32 GHz) (Fig. 7c and d).

In addition, novel hollow structure MOFs can also enlarge the transport path of internal electromagnetic waves to achieve encouraging absorption performance. A hierarchical carbon microcube with hollow cavities was fabricated by Han and co-workers.86 The unique microstructure with a larger specific surface area and pore volume improves the overall dielectric loss capacity. The minimum RL reached −60.7 dB at 6.9 GHz and 1.5 mm (Fig. 7e and f). Moreover, Liu et al. synthesized MOF-derived Co/CoO particles via hydrogen reduction at relatively low temperatures.87 The tunable electromagnetic properties and good impedance matching endow the material with excellent MA capacity and wide band absorption response, and the RL reaches −87.2 dB at 1 mm corresponding to a bandwidth of 6.2 GHz.

4.2. Zn-based absorbers

ZIF-8 is also an important member of the MOF family. Ji et al. grew ZIF-8 particles in 3DPCNs to synthesize multiporous network nanostructure electromagnetic wave absorbers, as shown in Fig. 8a–f.88 The composites show appropriate electrical conductivity and excellent impedance matching, achieving strong microwave absorption (Fig. 8g and h). The optimal RL reaches −35.7 dB with a corresponding thickness of 2.35 mm and a 10 wt% filler loading (Fig. 8i). This novel structure allows more microwaves to be attenuated, which proved that ZIF-8 can be used as an ideal template for carbonization.
image file: d1qm00659b-f8.tif
Fig. 8 (a and b) Formation process of 3DPCNs and ZnO@NPC/3DPCN hybrids. SEM images of 3DPCNs (c) and S-600 (d), and TEM image (e) and HRTEM image (f) of S-600. (g and h) Plots of ε′ and ε′′ of all samples. (i) RL values of the S-600. Reproduced from ref. 88 with permission. Copyright 2019, ACS.

Unlike Co ions, Zn ions in ZIF-8 will volatilize and cannot obtain magnetic metals or metal oxides after carbonization at high temperature. And the wave absorption performance of ZIF-8 is limited due to the poor magnetic loss. In order to solve this problem, a magnetic medium was introduced into ZIF-8 and its derivatives to improve the magnetic loss and impedance matching. Zhang and co-workers synthesized Co3O4/ZIF-8 precursors by blending Co3O4 nanoparticles with ZIF-8 nanoparticles via a simple grinding method.89 In this nanocomposite, the additional magnetic properties and porous surface structure enhance the microwave absorption performance. The minimum RL reached −31.53 dB at 6.3 GHz.

4.3. Ni-based absorbers

Besides Co and Zn, Ni is one of the most common transition metal elements that have shown promising electromagnetic absorbing performance. Liu et al. used nickel as the metal element to adjust the structure and properties of MOF materials.90 The Ni-ZIF precursor was synthesized by the hydrothermal method and then it was pyrolyzed under an argon atmosphere. The good impedance matching, microwave attenuation, multiple reflection and interface polarization have significantly improved the wave absorption performance of the Ni@C-ZIF, which shows a strong reflection loss of −86.8 dB at 13.2 GHz and a broad absorption bandwidth of 7.4 GHz. On this basis, the combination of Ni-ZIF with MXene to form an accordion-like Ni-CZIF is further developed.91 The MXene@Ni@-CZIF combines the advantages of these two materials, promoted magnetic loss and improved impedance matching. Further, the space charge polarization, multiple interface scattering and reflection enhance the dielectric relaxation for excellent MA properties. The minimum RL reached −64.11 dB at 5.12 mm.

In addition, Yang and co-workers recently demonstrated that the mixed organic ligands could further tune the structure and properties of MOFs.92 The micro-morphology and microwave absorption properties of the ML-Ni MOF are greatly affected by the molar ratios of the organic ligands. When the molar ratio of C9H6O6 to C4H4N2 is 2[thin space (1/6-em)]:[thin space (1/6-em)]2 mmol, the optimal RL can reach −65.33 dB with an effective bandwidth of 7.6 GHz.

4.4. Fe-based absorbers

Chen et al. demonstrated that Fe-MOF possesses excellent microwave absorption properties for the first time.93 The Fe-MOF is successfully synthesized by the hydrothermal method. The optimal RL can reach −54.2 dB at 2.65 mm. Unlike other MOF-based materials, the excellent microwave absorption of Fe-MOF is due to the inherent electrical relaxation instead of magnetic relaxation. The rotation of polar groups or regions inside the Fe-MOF is the key to high electromagnetic response.

Additionally, the MIL-100(Fe)-driven porous iron with prominent absorption performance was fabricated via a thermal decomposition method.94 Due to the multiple reflection and scattering loss and interface polarization of the porous ions, MAA-750 iron could effectively broaden the effective bandwidth. The optimal RL reaches −75.3 dB at 7.3 GHz. Lately, Liu's group grew MIL-53(Fe) derived γ-Fe2O3 on the graphene nanosheets by a facile hydrothermal method and gradient temperature calcination.95 The introduction of γ-Fe2O3 not only bring extra magnetic loss, but also optimize the impedance matching, improving the electromagnetic properties. The optimal RL reaches −62.53 dB with a thickness of 2.66 mm.

4.5. Bimetallic absorbers

Bimetallic MOFs are adjustable in the metal center and ligand structure and have a better attenuation property of electromagnetic energy. Thus, they are also an ideal self-sacrificing template for preparing excellent microwave carbon absorbing materials.78 Compared with single-metal MOFs, multi-metal MOFs have a variety of topological structures, which increase the electromagnetic parameters that can be adjusted. In general, the microwave absorption performance of polymetallic MOF derivatives is better than that of mono-metallic MOF derivatives.45 Therefore, the electromagnetic microwave absorption properties of the MOFS-derived composite have been studied.

In 2019, Chen's group grew Co and Zn-containing N-doped carbon nanotubes on the graphene to adjust the absorber's dielectric loss and impedance matching characteristics by changing the metal composition (Fig. 9).96 The optimal RL reaches −47.31 dB at 4.01 GHz and 6 wt%, superior to most reported materials. Inspired by the structure of the cactus, Xu et al. rationally designed a bi-ZIF derived hierarchical Co/N-decorated carbon architecture comprising CNTs grafted on carbon flakes. The high-efficiency microwave absorption originates from the enhanced multiple reflection and optimized impedance matching.97 The optimal RL reaches −44.6 dB at 5.20 GHz and 15 wt%. Innovatively, Wu et al. pyrolyzed the ultrathin 2D-MOF nanosheets to derive the porous Co/Ni/C composite.98 The high surface area, conductivity, and shape anisotropy make it have excellent EMW absorbing performance, with an RL of −49.8 dB and an effective adsorption bandwidth of 7.6 GHz.


image file: d1qm00659b-f9.tif
Fig. 9 (a) Schematic illustration of the formation process of CoZn@NCNTHS/G. SEM images of (b) CoZn-MOF/G, (c) CoZn@NCNTHS and (d) CoZn@NCNTHS/G-700. Plots of (e) tan[thin space (1/6-em)]δe and (f) tan[thin space (1/6-em)]δm. (g) RL values of the CoZn@NCNTHS/G-700. Reproduced from ref. 80 with permission. Copyright 2019, Elsevier.

4.6. Others

Cu-MOF is also a probable candidate for excellent microwave absorbing materials. For example, an octahedral Cu9S5/C composite was constructed by Liu and co-workers using HKUST-1 precursor, followed by carbonization and sulfidation processes.99 The adjustable components play an important role in excellent absorption performance with a good RL of −62.3 dB and a broad bandwidth of 4.7 GHz. Liu et al. demonstrated that Mn-MOF would offer new opportunities for microwave absorbing materials.100 The Mn-MOF derivative shows excellent electromagnetic response in the full band. The optimal RL value reaches −63.21 dB at 12.48 GHz.

Additionally, the green and environment friendly CD-MOF could be fabricated via the coordination reaction between alkaline metal ions and cyclodextrins. A hierarchical porous carbon is acquired using a novel CD-MOF-K template via the carbonization process.101 The electromagnetic properties of the formed porous carbon are tuned by adjusting the prepared conditions. Even without doping toxic metals such as Co and Ni, the CD-MOF derived HPC exhibits optimal absorption performance, achieving −23.5 dB.

5. Application in electromagnetic interference shielding

Compared with MOF-based absorbing materials, the development of MOF-based shielding materials is still at the initial stage and is far from practical application. MOFs can easily obtain carbon-based materials modified with highly dispersed heterogeneous metals and other species (such as CNTs and nanowires) during the carbonization process, which will further enhance EMI shielding capability.45,78 Therefore, it is necessary to explore the magnetic metal-carbon materials derived from MOFs in the field of EMI shielding in order to achieve a significant shielding effect and enhance EM wave absorption.

3D interconnected network structures, such as aerogels, foam and sponges, not only provide high specific surfaces and low densities, but also have rich pores that can enhance microwave energy dissipation in EMI shielding properties.102,103 For example, Chen et al. reported a novel light-weight Co/C@cellulose nanofiber (CNF) with low specific weight and outstanding EMI shielding ability via freeze-drying and carbonization.104 The cobalt magnetic nanoparticles embedded in the carbon sheet and the 3D interconnection network enhance the magnetic loss and dielectric loss capacity. The obtained Co/C@CNF aerogel exhibits the highest effectiveness of 35.1 dB at a density of only 1.74 mg cm−3, with a good specific SE of 20172.4 dB cm3 g−1. Subsequently, the bacterial cellulose gel served as nucleation centers for growing ZIF-67 crystals to construct a new CNF (CNF@Co/C) aerogel with polyhedral Co/C particles embedded.105 The 3D interconnected network, porous structure, abundant interface, and the synergies between dielectric carbon species and magnetic metal crystals contribute to a high-effective microwave absorption together. The flexible CNF@Co/C aerogel shows the comprehensive EMI SE performance with a maximum EMI SE of 56.07 dB at a density of only 0.023 g cm−3, as shown in Fig. 10. These two works provide new insights into the development of lightweight electromagnetic shielding materials and devices.


image file: d1qm00659b-f10.tif
Fig. 10 (a) Fabrication process of the CNF@Co/C aerogel. (b) Photo and (c) SEM images of the CNF@Co/C aerogel. (d) EMI shielding mechanism. (e) Average SET, SEA and SER. (f) Average A, R and T. Reproduced from ref. 105 with permission. Copyright 2020, Elsevier.

3D graphene foam (GF) has been widely used as a conductive filler of EMI shielding composites. Novel and flexible foam was fabricated by combining ZIF-8 derived magnetic and electron conducting components with GF networks.106 The ZIF-8 modified with Fe(Acac)3 molecules further generates a uniformly dispersed Fe nanoparticle/CNT network during a pyrolysis process. The FCC-GF-PDMS achieves the highest effectiveness of 48 dB, with a corresponding specific EMI SE of 20[thin space (1/6-em)]172.4 dB cm3 g−1. This significantly high EMI shielding property is due to integrated dielectric and magnetic losses and synergies between FCC and graphene foam. Therefore, this work provides a broad application prospect for flexible, lightweight, and high-performance shielding materials. In addition, Thi and co-workers fabricated a novel structure material for EMI application inspired by the thorny trunk.107 The rGO@HKUST-1 achieves the best EMI SE performance with a maximum SET of 46.1 dB.

Moreover, the design of multi-layer structures is also an effective method to improve electromagnetic absorption and shielding capability. In 2020, Chen's group reported a sandwich-like C-MIL-88B/GNP via a vacuum-assisted filtration process.108 After pyrolysis of Fe-MOFs, Fe3O4 particles are successfully dispersed in the carbon matrix. The C-MIL-88B/GNP composite films with different layers are synthesized via a layer-by-layer assembly approach. Among them, the composite membrane with five layers achieves the best shielding efficiency of 28 dB with an absorption coefficient of up to 86% due to its various polarizations and resonances. This novel multilayer structure with efficient electromagnetic (EM) shielding and high EM wave (EMW) absorption is expected to meet the further requirements in the upcoming 5G era.

6. Conclusions and outlook

Microstructure optimization is becoming a very hot topic in nanoscience and nanotechnology, as it offers immense potential for breaking through the bottleneck of designing highly efficient MOF-based electromagnetic materials. Tailoring MOF architectures, including composition and structure, provides a large flexibility for adjusting the high-efficiency electromagnetic properties. Thus, the well-designed MOF architecture with multiple loss mechanisms is an attractive direction of future electromagnetic functional materials. Currently, the absorption ability of MOF-based absorbers has increased from an initial −20 dB to about −90 dB, which is a significant breakthrough in this field. Moreover, the effective bandwidth can cover multiple frequency bands at a specific thickness. Table 1 summarizes the microwave absorption properties of current reported MOF-based absorbers.
Table 1 Microwave absorption performance of MOF-based materials and some popular materials
Material Adding mass (wt%) RL min (dB) Thickness (mm) EAB (GHz) Ref.
NC-Co3O4/CP 40 −41.38 2.3 — 84
MOFs/SiC 10 −47 2.0 5.92 85
HPCMCs-2 30 −60.7 1.5 14.4 86
Co/CoO 50 −87.2 1 6.2 87
ZnO@NPC/3DPCN 10 −35.7 2.35 2.75 88
Ni@C-ZIF 40 −86.8 2.7 7.4 90
MXene@Ni-CZIF 50 −60.09 2.7 9.3 91
MA-750 30 −75.3 3.3 4 94
γ-Fe2O3/C 50 −62.53 2.66 5.2 95
CoZn@NCNTHS/G-700 6 −47.31 1.5 4.01 96
CoNC/CNT-3/1 15 −44.6 1.5 4.5 97
Cu9S5/C 45 −62.3 1.3 4.7 99
MnO2@NPC 50 −63.21 12.48 4.04 100
rGO@NiO/ZnO 70 −42.5 2.15 4.5 109
MMOF/MOF 30 −36 2 5 110

However, there are still considerable challenges to be overcome. Except those well-studied MOFs, such as PBA and ZIF, other low-cost, easily synthesized MOF materials also need to be further explored. Next, the growth mechanism of MOFs should be further explored to precisely customize the formation of nanostructures and their hierarchical superstructure. Furthermore, the dissection of the electromagnetic loss mechanism inside MOFs still requires further investigations. Despite these challenges, we strongly believe that MOF-based materials have special advantages and are promising for future electromagnetic applications. Theoretical calculations and modeling based on density functional theory (DFT) might help to understand the relation between complex nanostructures and their electromagnetic properties. In addition, with the rapid development of nanoscience and nanotechnology, the advanced synthetic and characterization methods will bring opportunities to facile preparation methods to fabricate MOF-based electromagnetic functional materials with desired structures and properties. The future research should emphasize the development of controllable and low-cost preparation methods for large-scale production and practical application. Finally, the MOF-based electromagnetic devices would be another potential development trend in future research. The introduction of flexibility is expected to achieve flexible and wearable devices. For example, a flexible device has been fabricated by depositing MOFs on a conductive carbon substrate, which may offer illumination for future MOF-based device manufacturing. In summary, the tailoring of the complex MOF architecture is in the stage of vigorous development. We optimistically anticipate that the novel nanostructures and hierarchical superstructure generated by MOF-based materials will lead to breakthroughs in the vast field of electromagnetism, and novel ultra-efficient absorption and shielding materials can be realized.

Conflicts of interest

The authors declare no conflict of interest.

Acknowledgements

Financial support from the National Natural Science Foundation of China (Grant No. 51977009, 11774027, and 51132002) is gratefully acknowledged.

References

  1. M. S. Cao, X. X. Wang, M. Zhang, J. C. Shu, W. Q. Cao, H. J. Yang, X. Y. Fang and J. Yuan, Electromagnetic response and energy conversion for functions and devices in low-dimensional materials, Adv. Funct. Mater., 2019, 29, 1807398 CrossRef .
  2. O. Balci, E. O. Polat, N. Kakenov and C. Kocabas, Graphene-enabled electrically switchable radar-absorbing surfaces, Nat. Commun., 2015, 6, 6628 CrossRef CAS PubMed .
  3. Z. M. Dang, J. K. Yuan, J. W. Zha, T. Zhou, S. T. Li and G. H. Hu, Fundamentals, processes and applications of high-permittivity polymer-matrix composites, Prog. Mater. Sci., 2012, 57, 660–723 CrossRef CAS .
  4. M. Zhang, M. S. Cao, J. C. Shu, W. Q. Cao, L. Li and J. Yuan, Electromagnetic absorber converting radiation for multifunction, Mater. Sci. Eng., R, 2021, 145, 100627 CrossRef .
  5. D. Ding, Y. Wang, X. D. Li, R. Qiang, P. Xu, W. L. Chu, X. J. Han and Y. C. Du, Rational design of core-shell Co@C microspheres for high-performance microwave absorption, Carbon, 2017, 111, 722–732 CrossRef CAS .
  6. A. Ohlan, K. Singh, A. Chandra and S. K. Dhawan, Microwave absorption behavior of core-shell structured poly(3,4-ethylenedioxy thiophene)-barium ferrite nanocomposites, ACS Appl. Mater. Interfaces, 2010, 2(3), 927–933 CrossRef CAS PubMed .
  7. R. Peymanfar, A. Ahmadi, E. Selseleh-Zakerin, A. Ghaffari, M. M. Mojtahedi and A. Sharifi, Electromagnetic and optical characteristics of wrinkled Ni nanostructure coated on carbon microspheres, Chem. Eng. J., 2021, 405, 126985 CrossRef CAS .
  8. A. Kolanowska, D. Janas, A. P. Herman, R. G. Jędrysiak, T. Giżewski and S. Boncel, From blackness to invisibility – Carbon nanotubes role in the attenuation of and shielding from radio waves for stealth technology, Carbon, 2018, 126, 31–52 CrossRef CAS .
  9. F. Wu, A. M. Xie, M. X. Sun, Y. Wang and M. Y. Wang, Reduced graphene oxide (RGO) modified spongelike polypyrrole (PPy) aerogel for excellent electromagnetic absorption, J. Mater. Chem. A, 2015, 2, 14358 RSC .
  10. Y. Cheng, H. Q. Zhao, H. L. Lv, T. F. Shi, G. B. Ji and Y. L. Hou, Lightweight and flexible cotton aerogel composites for electromagnetic absorption and shielding applications, Adv. Electron. Mater., 2019, 6, 1900796 CrossRef .
  11. M. Zhou, W. H. Gu, G. H. Wang, J. Zheng, C. C. Pei, F. Y. Fan and G. B. Ji, Sustainable wood-based composites for microwave absorption and electromagnetic interference shielding, J. Mater. Chem. A, 2020, 8, 24267 RSC .
  12. X. X. Wang, J. C. Shu, W. Q. Cao, M. Zhang, J. Yuan and M. S. Cao, Eco-mimetic nanoarchitecture for green EMI shielding, Chem. Eng. J., 2019, 369, 1068–1077 CrossRef CAS .
  13. T. Kim, H. W. Do, K.-J. Choi, S. Kim, M. Lee, T. Kim, B.-K. Yu, J. Cheon, B.-W. Min and W. Shim, Layered Aluminum for Electromagnetic Wave Absorber with Near-Zero Reflection, Nano Lett., 2021, 21(2), 1132–1140 CrossRef CAS PubMed .
  14. L. P. Wu, F. Wu, Q. Y. Sun, J. Y. Shi, A. M. Xie, X. F. Zhu, W. Dong and A. TTF-TCNQ, complex: an organic charge-transfer system with extraordinary electromagnetic response behavior, J. Mater. Chem. C, 2021, 9, 3316–3323 RSC .
  15. J. Zhang, Z. Gao, S. Wang, G. Wang, X. Gao, B. Zhang, S. Xing, S. Zhao and Y. Qin, Origin of synergistic effects in bicomponent cobalt oxide-platinum catalysts for selective hydrogenation reaction, Nat. Commun., 2019, 10, 4166 CrossRef PubMed .
  16. J.-Z. He, X.-X. Wang, Y.-L. Zhang and M.-S. Cao, Small magnetic nanoparticles decorating reduced graphene oxides to tune the electromagnetic attenuation capacity, J. Mater. Chem. C, 2016, 4, 7130–7140 RSC .
  17. N. Gandhi, K. Singh, A. Ohlan, D. P. Singh and S. K. Dhawan, Thermal, dielectric and microwave absorption properties of polyaniline–CoFe2O4 nanocomposites, Compos. Sci. Technol., 2011, 71(15), 1754–1760 CrossRef CAS .
  18. M. Zhang, X.-X. Wang, W. Q. Cao, J. Yuan and M.-S. Cao, Electromagnetic functions of patterned 2D materials for micro-nano devices covering GHz, THz, and optical frequency, Adv. Opt. Mater., 2019, 7, 1900689 CrossRef CAS .
  19. G. Z. Wang, X. G. Peng, L. Yu, G. P. Wan, S. W. Lin and Y. Qin, Enhanced microwave absorption of ZnO coated with Ni nanoparticles produced by atomic layer deposition, J. Mater. Chem. A, 2015, 3, 2734–2740 RSC .
  20. Y. P. Wang, B. Sou, Y. A. Shi, H. R. Yuan, C. L. Zhu and Y. J. Chen, General fabrication of 3D hierarchically structured bamboo-like nitrogen-doped carbon nanotube arrays on 1D nitrogen-doped carbon skeletons for highly efficient electromagnetic wave energy attenuation, ACS Appl. Mater. Interfaces, 2020, 12, 40692–40701 CrossRef CAS PubMed .
  21. B. Shin, S. Mondal, M. Lee, S. Kim, Y.-I. Huh and C. Nah, Flexible thermoplastic polyurethane-carbon nanotube composites for electromagnetic interference shielding and thermal management, Chem. Eng. J., 2021, 418, 129282 CrossRef CAS .
  22. O. M. Yaghi, G. Li and H. Li, Selective binding and removal of guests in a microporous metal–organic framework, Nature, 1995, 378, 703–706 CrossRef CAS .
  23. H. Furukawa, K. E. Cordova, M. O’Keeffe and O. M. Yaghi, The Chemistry and Applications of Metal–Organic Frameworks, Science, 2013, 341(6149), 1230444 CrossRef PubMed .
  24. K. I. Hadjiivanov, D. A. Panayotov, M. Y. Mihaylov, E. Z. Ivanova, K. K. Chakarova, S. M. Andonova and N. L. Drenchev, Power of Infrared and Raman Spectroscopies to Characterize Metal–Organic Frameworks and Investigate Their Interaction with Guest Molecules, Chem. Rev., 2021, 121(3), 1286–1424 CrossRef CAS PubMed .
  25. U. Ryu, S. Jee, P. C. Rao, J. Shin, C. Ko, M. Yoon, K. S. Park and K. M. Choi, Recent advances in process engineering and upcoming applications of metal–organic frameworks, Coord. Chem. Rev., 2021, 426, 213544 CrossRef CAS PubMed .
  26. A. Muthurasu, V. Maruthapandian and H. Y. Kim, Metal–organic framework derived Co3O4/MoS2 heterostructure for efficient bifunctional electrocatalysts for oxygen evolution reaction and hydrogen evolution reaction, Appl. Catal., B, 2019, 248, 202–210 CrossRef CAS .
  27. S. S. Shinde, C. H. Lee, J.-Y. Jung, N. K. Wagh, S.-H. Kim, D.-H. Kim, C. Lin, S. U. Lee and J.-H. Lee, Unveiling dual-linkage 3D hexaiminobenzene metal–organic frameworks towards long-lasting advanced reversible Zn–air batteries, Energy Environ. Sci., 2019, 12(2), 727–738 RSC .
  28. M. R. Tchalala, P. M. Bhatt, K. N. Chappanda, S. R. Tavares, K. Adil, Y. Belmabkhout, A. Shkurenko, A. Cadiau, N. Heymans, G. De Weireld, G. Maurin, K. N. Salama and M. Eddaoudi, Fluorinated MOF platform for selective removal and sensing of SO2 from flue gas and air, Nat. Commun., 2019, 10(1), 1328 CrossRef CAS PubMed .
  29. H. Yuan, S. A. A. A. Aljneibi, J. Yuan, Y. Wang, H. Liu, J. Fang, C. Tang, X. Yan, H. Cai, Y. Gu, S. J. Pennycook, J. Tao and D. Zhao, ZnO Nanosheets Abundant in Oxygen Vacancies Derived from Metal–Organic Frameworks for ppb-Level Gas Sensing, Adv. Mater., 2019, 31(11), 1807161 CrossRef PubMed .
  30. L. Zhang, X. Shi, Z. Zhang, R. P. Kuchel, R. Namivandi-Zangeneh, N. Corrigan, K. Jung, K. Liang and C. Boyer, Porphyrinic Zirconium Metal–Organic Frameworks (MOFs) as Heterogeneous Photocatalysts for PET-RAFT Polymerization and Stereolithography, Angew. Chem., Int. Ed., 2021, 60(10), 5489–5496 CrossRef CAS PubMed .
  31. U. Ryu, S. Jee, P. C. Rao, J. Shin, C. Ko, M. Yoon, K. S. Park and K. M. Choi, Recent advances in process engineering and upcoming applications of metal–organic frameworks, Coord. Chem. Rev., 2021, 426, 213544 CrossRef CAS PubMed .
  32. S. Yuan, L. Feng, K. Wang, J. Pang, M. Bosch, C. Lollar, Y. Sun, J. Qin, X. Yang, P. Zhang, Q. Wang, L. Zou, Y. Zhang, L. Zhang, Y. Fang, J. Li and H.-C. Zhou, Stable metal–organic frameworks: design, synthesis, and applications, Adv. Mater., 2018, 30, 1704303 CrossRef PubMed .
  33. Z. Zhang, Z. Cai, Z. Wang, Y. Peng, L. Xia, S. Ma, Z. Yin and Y. Huang, A Review on metal–organic framework-derived porous carbon-based novel microwave absorption materials, Nano-Micro Lett., 2021, 13, 56 CrossRef PubMed .
  34. S. Bibi, E. Pervaiz and M. Ali, Synthesis and applications of metal oxide derivatives of ZIF-67: a mini-review, Chem. Pap., 2021, 75(6), 2253–2275 CrossRef CAS .
  35. M. Green and X. Chen, Recent progress of nanomaterials for microwave absorption, J. Materiomics, 2019, 5(4), 503–541 CrossRef .
  36. L. Wang, Y. Guan, X. Qiu, H. Zhu, S. Pan, M. Yu and Q. Zhang, Efficient ferrite/Co/porous carbon microwave absorbing material based on ferrite@metal–organic framework, Chem. Eng. J., 2017, 326, 945–955 CrossRef CAS .
  37. Y. Z. Jiao, S. Y. Cheng, F. Wu, X. H. Pan, A. M. Xie, X. F. Zhu and W. Dong, MOF-Guest complex derived Cu/C nanocomposites with multiple heterogeneous interfaces for excellent electromagnetic waves absorption, Composites, Part B, 2021, 211, 108643 CrossRef CAS .
  38. L. Wang, M. Q. Huang, X. F. Yu, W. B. You, J. Zhang, X. H. Liu, M. Wang and R. C. Che, MOF-derived Ni1−xCox@carbon with tunable nano-microstructure as lightweight and highly efficient electromagnetic wave absorber, Nano-Micro Lett., 2020, 12, 150 CrossRef CAS PubMed .
  39. S. Furukawa, J. Reboul, S. Diring, K. Sumida and S. Kitagawa, Structuring of metal–organic frameworks at the mesoscopic/macroscopic scale, Chem. Soc. Rev., 2014, 43, 5700–5734 RSC .
  40. L. Feng, K.-Y. Wang, J. Powell and H.-C. Zhou, Controllable synthesis of metal–organic frameworks and their hierarchical assemblies, Matter, 2019, 1, 801–824 CrossRef .
  41. B. Y. Guan, X. Y. Yu, H. B. Wu and X. W. Lou, Complex Nanostructures from Materials based on Metal–organic frameworks for electrochemical energy storage and conversion, Adv. Mater., 2017, 29, 1703614 CrossRef PubMed .
  42. Y. V. Kaneti, J. Tang, R. R. Salunkhe, X. Jiang, A. Yu, K. C.-W. Wu and Y. Yamauchi, Nanoarchitectured design of porous materials and nanocomposites from metal–organic frameworks, Adv. Mater., 2017, 29, 1604898 CrossRef PubMed .
  43. J. Nai and X. W. Lou, Hollow structures based on prussian blue and its analogs for electrochemical energy storage and conversion, Adv. Mater., 2019, 31, 1706825 CrossRef PubMed .
  44. D. Liu, J. Wan, G. Pang and Z. Tang, Hollow metal–organic-framework micro/nanostructures and their derivatives: emerging multifunctional materials, Adv. Mater., 2019, 31, 1803291 CrossRef PubMed .
  45. J. C. Shu, X. Y. Yang, X. R. Zhang, X. Y. Huang, M. S. Cao, L. Li, H. J. Yang and W. Q. Cao, Tailoring MOF-based materials to tune electromagnetic property for great microwave absorbers and devices, Carbon, 2020, 162, 157–171 CrossRef CAS .
  46. Y. Ma, S. Luo, M. Tian, J. E. Lu, Y. Peng, C. Desmond, Q. Liu, Q. Li, Y. Min, Q. Xu and S. Chen, Hollow carbon spheres codoped with nitrogen and iron as effective electrocatalysts for oxygen reduction reaction, J. Power Sources, 2020, 450, 227659 CrossRef CAS .
  47. H. Zhang, W. Zhang, J. Shen, Y. Li, X. Yan, J. Qi, X. Sun, J. Shen, W. Han, L. Wang and J. Li, Ag-doped hollow ZIFs-derived nanoporous carbon for efficient hybrid capacitive deionization, Desalination, 2020, 473, 114173 CrossRef .
  48. M. Chen, C. Peng, Y. Su, X. Chen, Y. Zhang, Y. Wang, J. Peng, Q. Sun, X. Liu and W. Huang, A general strategy for hollow metal-phytate coordination complex micropolyhedra enabled by cation exchange, Angew. Chem., Int. Ed., 2020, 59, 20988–20995 CrossRef CAS PubMed .
  49. W. Feng, Y. Wang, Y. Zou, J. Chen, D. Jia and Y. Zhou, ZnO@N-doped porous carbon/Co3ZnC core-shell heterostructures with enhanced electromagnetic wave attenuation ability, Chem. Eng. J., 2018, 342, 364–371 CrossRef CAS .
  50. S. Zhang, H. Gao, X. Xu, R. Cao, H. Yang, X. Xu and J. Li, MOF-derived CoN/N-C@SiO2 yolk-shell nanoreactor with dual active sites for highly efficient catalytic advanced oxidation processes, Chem. Eng. J., 2020, 381, 122670 CrossRef CAS .
  51. H. Chen, K. Shen, Q. Mao, J. Chen and Y. Li, Nanoreactor of MOF-derived yolk-shell Co@C-N: precisely controllable structure and enhanced catalytic activity, ACS Catal., 2018, 8, 1417–1426 CrossRef CAS .
  52. J. Wang, J. Wan, N. Yang, Q. Li and D. Wang, Hollow multishell structures exercise temporal-spatial ordering and dynamic smart behaviour, Nat. Rev. Chem., 2020, 4, 159–168 CrossRef .
  53. Y. Ding, L. Hu, D. He, Y. Peng, Y. Niu, Z. Li, X. Zhang and S. Chen, Design of multishell microsphere of transition metal oxides/carbon composites for lithium ion battery, Chem. Eng. J., 2020, 380, 122489 CrossRef CAS .
  54. F. Xie, L. Zhang, Q. Gu, D. Chao, M. Jaroniec and S.-Z. Qiao, Multi-shell hollow structured Sb2S3 for sodium-ion batteries with enhanced energy density, Nano Energy, 2019, 60, 591–599 CrossRef CAS .
  55. S. Jeoung, I. T. Ju, J. H. Kim, S. H. Joo and H. R. Moon, Hierarchically porous adamantane-shaped carbon nanoframes, J. Mater. Chem. A, 2018, 6, 18906–18911 RSC .
  56. C. Avci, J. Arinez-Soriano, A. Carne-Sanchez, V. Guillerm, C. Carbonell, I. Imaz and D. Maspoch, Post-synthetic anisotropic wet-chemical etching of colloidal sodalite ZIF crystals, Angew. Chem., Int. Ed., 2015, 54, 14417–14421 CrossRef CAS PubMed .
  57. X. Y. Yu, L. Yu, H. B. Wu and X. W. Lou, Formation of nickel sulfide nanoframes from metal–organic frameworks with enhanced pseudocapacitive and electrocatalytic properties, Angew. Chem., Int. Ed., 2015, 127, 1–6 CrossRef .
  58. L. Ji, J. Wang, X. Teng, T. J. Meyer and Z. Chen, CoP Nanoframes as bifunctional electrocatalysts for efficient overall water splitting, ACS Catal., 2019, 10, 412–419 CrossRef .
  59. S. L. Zhang, B. Y. Guan, X. F. Lu, S. Xi, Y. Du and X. W. D. Lou, Metal atom-doped Co3O4 hierarchical nanoplates for electrocatalytic oxygen evolution, Adv. Mater., 2020, 32, 2002235 CrossRef CAS PubMed .
  60. Y. Li, T. Zhao, M. Lu, Y. Wu, Y. Xie, H. Xu, J. Gao, J. Yao, G. Qian and Q. Zhang, Enhancing oxygen evolution reaction through modulating electronic structure of trimetallic electrocatalysts derived from metal–organic frameworks, Small, 2019, 15, 1901940 CrossRef CAS PubMed .
  61. H. Zhang, Q. Jiang, J. H. L. Hadden, F. Xie and D. J. Riley, Pd ion-exchange and ammonia etching of a prussian blue analogue to produce a high-performance water-splitting catalyst, Adv. Funct. Mater., 2020, 31, 2008989 CrossRef .
  62. Y. Zhao, C. Huang, Y. He, X. Wu, R. Ge, X. Zu, S. Li and L. Qiao, High-performance asymmetric supercapacitors realized by copper cobalt sulfide crumpled nanoflower and N, F co-doped hierarchical nanoporous carbon polyhedron, J. Power Sources, 2020, 456, 228023 CrossRef CAS .
  63. L. Han, X. Y. Yu and X. W. Lou, Formation of prussian-blue-analog nanocages via a direct etching method and their conversion into Ni–Co-mixed oxide for enhanced oxygen evolution, Adv. Mater., 2016, 28, 4601–4605 CrossRef CAS PubMed .
  64. B. Y. Guan, L. Yu and X. W. D. Lou, Formation of single-holed cobalt/N-doped carbon hollow particles with enhanced electrocatalytic activity toward oxygen reduction reaction in alkaline media, Adv. Sci., 2017, 4, 1700247 CrossRef PubMed .
  65. Y. Luo, M. Ahmad, A. Schug and M. Tsotsalas, Rising up: hierarchical metal–organic frameworks in experiments and simulations, Adv. Mater., 2019, 31, 1901744 CrossRef PubMed .
  66. P. Zhang, S. Wang, B. Y. Guan and X. W. Lou, Fabrication of CdS hierarchical multi-cavity hollow particles for efficient visible light CO2 reduction, Energy Environ. Sci., 2019, 12, 164–168 RSC .
  67. S. D. Seo, D. Park, S. Park and D. W. Kim, “Brain-Coral-Like” Mesoporous Hollow CoS2@N-doped graphitic carbon nanoshells as efficient sulfur reservoirs for lithium-sulfur batteries, Adv. Funct. Mater., 2019, 29, 1903712 CrossRef .
  68. C. C. Hou, L. Zou and Q. Xu, A hydrangea-like superstructure of open carbon cages with hierarchical porosity and highly active metal sites, Adv. Mater., 2019, 31, 1904689 CrossRef CAS PubMed .
  69. Y. M. Chen, L. Yu and X. W. Lou, Hierarchical tubular structures composed of Co3O4 hollow nanoparticles and carbon nanotubes for lithium storage, Angew. Chem., Int. Ed., 2016, 55, 5990–5993 CrossRef CAS PubMed .
  70. L. Yu, J. F. Yang and X. W. Lou, Formation of CoS2 nanobubble hollow prisms for highly reversible lithium storage, Angew. Chem., Int. Ed., 2016, 55, 13422–13426 CrossRef CAS PubMed .
  71. Z. Zhao, K. Kou and H. Wu, 2-Methylimidazole-mediated hierarchical Co3O4/N-doped carbon/short-carbon-fiber composite as high-performance electromagnetic wave absorber, J. Colloid Interface Sci., 2020, 574, 1–10 CrossRef CAS PubMed .
  72. S. Sun, X. Sun, Y. Liu, J. Peng, Y. Qiu, Y. Xu, J. Zhang, Q. Li, C. Fang, J. Han and Y. Huang, 3D hierarchical porous Co1−xS@C derived from a ZIF-67 single crystals self-assembling superstructure with superior pseudocapacitance, J. Mater. Chem. A, 2019, 7, 17248–17253 RSC .
  73. Z. Kang, M. Xue, L. Fan, J. Ding, L. Guo, L. Gao and S. Qiu, “Single nickel source” in situ fabrication of a stable homochiral MOF membrane with chiral resolution properties, Chem. Commun., 2013, 49, 10569–10571 RSC .
  74. C. Carbonell, I. Imaz and D. Maspoch, Single-crystal metal–organic framework arrays, J. Am. Chem. Soc., 2011, 13, 2144–2147 CrossRef PubMed .
  75. M. Yang, Y. Yuan, Y. Li, X. Sun, S. Wang, L. Liang, Y. Ning, J. Li, W. Yin, R. Che and Y. Li, Dramatically enhanced electromagnetic wave absorption of hierarchical CNT/Co/C fiber derived from cotton and metal–organic-framework, Carbon, 2020, 161, 517–527 CrossRef CAS .
  76. X. Deng, S. Zhu, F. He, E. Liu, C. He, C. Shi, Q. Li, J. Li, L. Ma and N. Zhao, Three-dimensionally hierarchical Co3O4/Carbon composites with high pseudocapacitance contribution for enhancing lithium storage, Electrochim. Acta, 2018, 283, 1269–1276 CrossRef CAS .
  77. J. Zhu, W. Tu, H. Pan, H. Zhang, B. Liu, Y. Cheng, Z. Deng and H. Zhang, Self-templating synthesis of hollow Co3O4 nanoparticles embedded in N,S-dual-doped reduced graphene oxide for lithium ion batteries, ACS Nano, 2020, 14, 5780–5787 CrossRef CAS PubMed .
  78. J. C. Shu, W. Q. Cao and M. S. Cao, Diverse metal–organic framework architectures for electromagnetic, absorbers and shielding, Adv. Funct. Mater., 2021, 31, 2100470 CrossRef CAS .
  79. M. S. Cao, W. L. Song, Z. L. Hou, B. Wen and J. Yuan, The effects of temperature and frequency on the dielectric properties, electromagnetic interference shielding and microwave-absorption of short carbon fiber/silica composites, Carbon, 2010, 48, 788–796 CrossRef CAS .
  80. M.-M. Lu, W.-Q. Cao, H.-L. Shi, X.-Y. Fang, J. Yang, Z.-L. Hou, H.-B. Jin, W.-Z. Wang, J. Yuan and M.-S. Cao, Multi-wall carbon nanotubes decorated with ZnO nanocrystals: mild solution-process synthesis and highly efficient microwave absorption properties at elevated temperature, J. Mater. Chem. A, 2014, 2, 10540–10547 RSC .
  81. M.-S. Cao, X.-X. Wang, M. Zhang, W. Q. Cao, X.-Y. Fang and J. Yuan, Variable-temperature electron transport and dipole polarization turning flexible multifunctional microsensor beyond electrical and optical energy, Adv. Mater., 2020, 32, 1907156 CrossRef CAS PubMed .
  82. B. Wen, M. S. Cao, Z. L. Hou, W. L. Song, L. Zhang, M. M. Lu, H. B. Jin, X. Y. Fang, W. Z. Wang and J. Yuna, Temperature dependent microwave attenuation behavior for carbon-nanotube/silica composites, Carbon, 2013, 65, 124–139 CrossRef CAS .
  83. M.-S. Cao, J.-C. Shu, X.-X. Wang, X. Wang, M. Zhang, H. J. Yang, X. Y. Fang and J. Yuan, Electronic structure and electromagnetic properties for 2D electromagnetic functional materials in gigahertz frequency, Ann. Phys., 2019, 531, 1800390 CrossRef CAS .
  84. B. Quan, X. Liang, X. Zhang, G. Xu, G. B. Ji and Y. Du, Functionalized carbon nanofibers enabling stable and flexible absorbers with effective microwave response at low thickness, ACS Appl. Mater. Interfaces, 2018, 10, 41535–41543 CrossRef CAS PubMed .
  85. K. Zhang, F. Wu, A. Xie, M. Sun and W. Dong, In situ stringing of metal organic frameworks by SiC nanowires for high-performance electromagnetic radiation elimination, ACS Appl. Mater. Interfaces, 2017, 9, 33041–33048 CrossRef CAS PubMed .
  86. H. Zhao, X. Xu, Y. Wang, D. Fan, D. Liu, K. Lin, P. Xu, X. Han and Y. Du, Heterogeneous interface induced the formation of hierarchically hollow carbon microcubes against electromagnetic pollution, Small, 2020, 16, 2003407 CrossRef CAS PubMed .
  87. Q. Wu, B. Wang, Y. Fu, Z. Zhang, P. Yan and T. Liu, MOF-derived Co/CoO particles prepared by low temperature reduction for microwave absorption, Chem. Eng. J., 2021, 410, 128378 CrossRef CAS .
  88. X. Liang, B. Quan, Z. Man, B. Cao, N. Li, C. Wang, G. Ji and T. Yu, Self-assembly three-dimensional porous carbon networks for efficient dielectric attenuation, ACS Appl. Mater. Interfaces, 2019, 11, 30228–30233 CrossRef CAS PubMed .
  89. Q. Wu, J. Wang, H. Jin, Y. Dong, S. Huo, S. Yang, X. Su and B. Zhang, Facile synthesis of Co-embedded porous spherical carbon composites derived from Co3O4/ZIF-8 compounds for broadband microwave absorption, Compos. Sci. Technol., 2020, 195, 108206 CrossRef CAS .
  90. J. Yan, Y. Huang, Y. Yan, L. Ding and P. Liu, High-performance electromagnetic wave absorbers based on two kinds of nickel-based MOF-derived Ni@C microspheres, ACS Appl. Mater. Interfaces, 2019, 11, 40781–40792 CrossRef CAS PubMed .
  91. X. Han, Y. Huang, L. Ding, Y. Song, T. Li and P. Liu, Ti3C2Tx MXene nanosheet/metal–organic framework composites for microwave absorption, ACS Appl. Nano Mater., 2020, 4, 691–701 CrossRef .
  92. Y. Qiu, H. Yang, Y. Cheng, X. Bai, B. Wen and Y. Lin, Constructing a nitrogen-doped carbon and nickel composite derived from a mixed ligand nickel-based a metal–organic framework toward adjustable microwave absorption, Nanoscale, 2021, 13, 9204–9216 RSC .
  93. M. Green, Z. Liu, P. Xiang, X. Tan, F. Huang, L. Liu and X. Chen, Ferric metal–organic framework for microwave absorption, Mater. Today Chem., 2018, 9, 140–148 CrossRef CAS .
  94. T. Zhu, Y. Sun, Y. Wang, H. Xing, X. Li, P. Hu, Y. Zong and X. Zheng, A MOF-driven porous iron with high dielectric loss and excellent microwave absorption properties, J. Mater. Sci.: Mater. Electron., 2020, 31, 6843–6854 CrossRef CAS .
  95. L. Ding, Y. Huang, Z. Xu, J. Yan, X. Liu, T. Li and P. Liu, MIL-53(Fe) derived MCC/rGO nanoparticles with excellent broadband microwave absorption properties, Compos. Commun., 2020, 21, 100362 CrossRef ; L. Ding, Y. Huang, Z. Xu, J. Yan, X. Liu, T. Li and P. Liu, MIL-53(Fe) derived MCC/rGO nanoparticles with excellent broadband microwave absorption properties, Compos. Commun., 2020, 21, 100362 CrossRef .
  96. X. Zhang, J. Xu, X. Liu, S. Zhang, H. Yuan, C. Zhu, X. Zhang and Y. Chen, Metal organic framework-derived three-dimensional graphene-supported nitrogen-doped carbon nanotube spheres for electromagnetic wave absorption with ultralow filler mass loading, Carbon, 2019, 155, 233–242 CrossRef CAS .
  97. X. Xu, F. Ran, Z. Fan, H. Lai, Z. Cheng, T. Lv, L. Shao and Y. Liu, Cactus-inspired bimetallic metal–organic framework-derived 1D-2D hierarchical Co/N-decorated carbon architecture toward enhanced electromagnetic wave absorbing performance, ACS Appl. Mater. Interfaces, 2019, 11, 13564–13573 CrossRef CAS PubMed .
  98. G. Liu, J. Tu, C. Wu, Y. Fu, C. Chu, Z. Zhu, X. Wang and M. Yan, High-Yield Two-Dimensional Metal–Organic Framework Derivatives for Wideband Electromagnetic Wave Absorption, ACS Appl. Mater. Interfaces, 2021, 13, 20459–20466 CrossRef CAS PubMed .
  99. D. Xu, Y. Yang, K. Le, G. Wang, A. Ouyang, B. Li, W. Liu, L. Wu, Z. Wang, J. Liu and F. Wang, Bifunctional Cu9S5/C octahedral composites for electromagnetic wave absorption and supercapacitor applications, Chem. Eng. J., 2021, 417, 129350 CrossRef CAS .
  100. H. Yang, Z. Shen, H. Peng, Z. Xiong, C. Liu and Y. Xie, 1D-3D mixed-dimensional MnO2@nanoporous carbon composites derived from Mn-metal organic framework with full-band ultra-strong microwave absorption response, Chem. Eng. J., 2021, 417, 128087 CrossRef CAS .
  101. S. X. Zhang, L. Xu, Z. H. Chen, S. T. Fan, Z. J. Qiu, Z. J. Nie, B. J. Li and S. Zhang, Hierarchical porous carbon derived from green cyclodextrin metal–organic framework and its application in microwave absorption, J. Appl. Polym. Sci., 2021, 138, 50849 CrossRef CAS .
  102. A. Puthiyedath Narayanan, K. N. Narayanan Unni and K. Peethambharan, Surendran, Aerogels of V2O5 nanowires reinforced by polyaniline for electromagnetic interference shielding, Chem. Eng. J, 2021, 408, 127239 CrossRef CAS .
  103. Y. Yang, M. C. Gupta, K. L. Dudley and R. W. Lawrence, Novel Carbon Nanotube−Polystyrene Foam Composites for Electromagnetic Interference Shielding, Nano Lett., 2005, 5(11), 2131–2134 CrossRef CAS PubMed .
  104. Y. Fei, M. Liang, L. Yan, Y. Chen and H. Zou, Co/C@cellulose nanofiber aerogel derived from metal–organic frameworks for highly efficient electromagnetic interference shielding, Chem. Eng. J., 2020, 392, 124815 CrossRef CAS .
  105. Y. Fei, M. Liang, T. Zhou, Y. Chen and H. Zou, Unique carbon nanofiber@Co/C aerogel derived bacterial cellulose embedded zeolitic imidazolate frameworks for high-performance electromagnetic interference shielding, Carbon, 2020, 167, 575–584 CrossRef CAS .
  106. C. Yu, S. Zhu, C. Xing, X. Pan, X. Zuo, J. Liu, M. Chen, L. Liu, G. Tao and Q. Li, Fe nanoparticles and CNTs co-decorated porous carbon/graphene foam composite for excellent electromagnetic interference shielding performance, J. Alloys Compd., 2020, 820, 153108 CrossRef CAS .
  107. Q. V. Thi, N. Q. Nguyen, I. Oh, J. Hong, C. M. Koo, N. T. Tung and D. Sohn, Thorny trunk-like structure of reduced graphene oxide/HKUST-1 MOF for enhanced EMI shielding capability, Ceram. Int., 2021, 47(7), 10027–10034 CrossRef CAS .
  108. Y. Fei, M. Liang, Y. Chen and H. Zou, Sandwich-like magnetic graphene papers prepared with MOF-derived Fe3O4-C for absorption-dominated electromagnetic interference shielding, Ind. Eng. Chem. Res., 2019, 59, 154–165 CrossRef .
  109. Q. V. Thi, S. Park, J. Jeong, H. Lee, J. Hong, C. M. Koo, N. T. Tung and D. Sohn, A nanostructure of reduced graphene oxide and NiO/ZnO hollow spheres toward attenuation of electromagnetic waves, Mater. Chem. Phys., 2021, 266, 124530 CrossRef CAS .
  110. O. Mirzaee, I. Huynen and M. Zareinejad, Electromagnetic wave absorption characteristics of single and double layer absorbers based on trimetallic FeCoNi@C metal–organic framework incorporated with MWCNTs, Synth. Met., 2021, 271, 116634 CrossRef CAS .
This journal is © the Partner Organisations 2021
Click here to see how this site uses Cookies. View our privacy policy here.