Poly(dimethylsilylene)diacetylene-Guided ZIF-Based Heterostructures for Full Ku-Band Electromagnetic Wave Absorption

Abstract

Zeolitic imidazolate frameworks (ZIFs), a group of metal-organic frameworks (MOFs), hold promise as building blocks in electromagnetic (EM) wave absorption/shielding materials and devices. In this contribution, we proposed a facile strategy to synthesize three dimensional ZIF-67-based hierarchical heterostructures through coordinated reacting a preceramic component, poly(dimethylsilylene)diacetylenes (PDSDA) with ZIF-67, following by carbonizing the PDSDA wrapped ZIF at high temperature. The introduction of PDSDA leads to a controllable generation of surface network containing branched carbon nanotubes and regional distributed graphitic carbons, in addition to the nanostructures with well-defined size and porous surface made by cobalt nanoparticles. The surface structures can be tailored through variations in pyrolysis temperatures, therefore enabling a simple and robust route to facilitate suitable structural surface. The heterostructure of ZIF nanocomplex allows the existence of dielectric loss and magnetic loss, therefore, yielding a significant improvement on EM wave absorption with a minimum reflection coefficient (RCmin) of-50.9 dB at 17.0 GHz at a thickness of 1.9 mm and an effective absorption bandwidth (EAB) covering the full Ku-band (12.0 GHz to 18.0 GHz).

Transparent Electromagnetic Shielding Film Utilizing Imprinting-Based Micro Patterning Technology

“…Furthermore, research on a coating system using conductive particles has been carried out; it is revealed that changes in conductivity tend to occur according to the binder and curing properties. In order to maximize shielding performance, it is important to maximize the conductivity of the conductive composite [23]. In addition, in general, the proportion of conductive particles increases, but the flexibility decreases.…”

Highly efficient and broad electromagnetic wave absorbers tuned via topology-controllable metal-organic frameworks

“…For the carbon species in the nanocomplex, the Raman spectra in Figs 2h and 3h show two typical peaks at 1350 cm −1 (D band) and 1580 cm −1 (G band). As well known, D band is related to defect/disordered carbons and G band represents stretching vibration of sp 2 graphitic carbons, where the integral intensity ratio (I D /I G ) can be applied to evaluate the graphitization degree of carbons [20]. The I D /I G for solid Fe/Co/C-800, solid Fe/ Co/C-900, hollow Fe/Co/C-800 and hollow Fe/Co/C-900 (the number denotes pyrolytic temperature) were 1.24, 1.06, 1.42 and 1.15, respectively.…”

“…As expected, the derived Co/C composite with well-dispersed magnetic cobalt nanoparticles inherited the topological structure of ZIF-67 crystals, showing effective absorption even at high temperature, i.e., a minimum reflection loss (RL min ) of −35.3 dB and an effective absorption bandwidth (EAB) of 5.8 GHz measured at 500°C [15]. The modified ZIF-67-derived hybrids with SiC [16], ZIF-8 [17,18], MXene [19], poly(dimethylsilylene)diacetylene (PDSDA) [20], carbon nanotubes (CNTs) [21], multiwalled CNTs (MWCNTs) [22,23], V 2 O 3 [24], Co 9 S 8 [25], etc., were extensively studied. Meanwhile, other MOFs including two-dimensional (2D) Co-MOF [26], Co-MOF-74 [27], MIL-88A(Fe) [28], MIL-101(Fe) [29], CPT-1-Co [30], and Fe III -MOF-5 [31] with controllable topologies also received attentions in the fields of EM functional materials.…”

Adjustable iron‐containing SiBCN ceramics with high‐temperature microwave absorption and anti‐oxidation properties

“…[1][2][3][4][5] They mainly focus on ferrites, 6 low-dimensional carbon materials, 7,8 transition metals and their compounds, 9 and two-dimensional transition-metal carbides and nitrides (MXene). 10,11 At the same time, some novel light materials such as graphene or MXene aerogels have also been used to satisfy the requirements of EM wave-absorbing materials because of their high specific area and ultralow density. [12][13][14] However, at high temperatures, several problems such as oxidation of carbon materials transition from ferromagnetic to paramagnetic nature of magnetic materials above the Curie temperature have severely restricted their applications.…”

“…Electromagnetic (EM) wave‐absorbing materials with highly efficient and broadband absorption, light weight, and thin thickness are widely used to prevent EM pollution in various fields 1‐5 . They mainly focus on ferrites, 6 low‐dimensional carbon materials, 7,8 transition metals and their compounds, 9 and two‐dimensional transition‐metal carbides and nitrides (MXene) 10,11 . At the same time, some novel light materials such as graphene or MXene aerogels have also been used to satisfy the requirements of EM wave‐absorbing materials because of their high specific area and ultralow density 12‐14 .…”