Nanolayered Ceramic-Confined Graphene Aerogel with Conformal Heterointerfaces for Low-Frequency Microwave Absorption

Abstract

Graphene-based aerogels have garnered considerable attention for their lightweight and efficient microwave absorption (MA) properties; however, optimizing the relationship between impedance matching and attenuation capability at low frequencies remains a challenge. In this study, a three-dimensional (3D) silicon carbonitride (SiCN) nanoceramic-coated graphene aerogel with conformal heterogeneous interfaces is constructed by precursor infiltration and pyrolysis to optimize MA performance at low frequencies. Thanks to the enhanced impedance matching and significant interfacial polarization of the two-dimensional sandwiched SiCN/graphene/SiCN cell walls and multiple scattering occurring within the 3D porous skeleton, the aerogel achieves a minimum reflection loss of −57.9 dB at an ultralow frequency of 4.92 GHz (C-band) and a broad bandwidth of 5.0 GHz at an ultralow thickness of 1.7 mm. The strategy developed here provides a method for enhancing dielectric polarization loss in graphene aerogels by the joint optimization of interfacial polarization and impedance matching, inspiring the design of high-performance graphene-based materials for low-frequency MA.

Polymer-derived silicon oxycarbonitride bowls with hollow structures and hetero-nanodomains for electromagnetic wave absorption

“…13 Our recent work incorporated metal–organic frameworks into silicon carbonitride nanocomposite ceramics to regulate their dielectric genes, resulting in substantial lattice strain and ultradense lattice defects that induce intense interfacial and dipole polarizations. 18 Concurrently, unique multiscale structures such as nanospheres, 19 fibers, 20–22 aerogels, 23–27 and metamaterials 28–31 have been conceived and realized. For instance, the hierarchical pore structure endowed the silicon oxycarbonitride (SiOCN) aerogel with a broad bandwidth at a low thickness.…”

Intelligent Tunable Wave-Absorbing CNTs/VO2/ANF Composite Aerogels Based on Temperature-Driving

“…However, increasing electromagnetic wave (EMW) pollution and radiation also cause threats to human health and information security. The urgent demand on how to deal with EMW pollution and absorb EMW radiation efficiently has raised great concerns about the development of efficient EMW absorbing materials. − In recent years, many traditional materials such as carbon-based materials (graphene, carbon nanotubes), conductive polymers (ferrites, alloys), and metal-based materials have been applied to electromagnetic wave absorption (EMA) strategies. , Graphene is a two-dimensional structure composed of a single layer of carbon atoms with excellent high electrical conductivity and mechanical strength but is currently expensive to prepare on a large scale and prone to structural changes at high temperatures, affecting performance . Carbon nanotubes have shown great strengths in electromagnetic wave-absorbing materials due to their excellent electrical and thermal conductivity, light weight, and good stability; however, they are easy to agglomerate, are difficult to disperse in the substrate, and have a large dielectric constant, which is not conducive to impedance matching. − The physical properties of aerogels with ultralow density, high porosity, large specific surface area, and low dielectric constant have great potential for modulating EMA. − …”

Fabrication of iron manganese metal–organic framework derived magnetic MnFe2O4/C composites for broadband and highly efficient electromagnetic wave absorption

“…1,2 Meanwhile, the problem resulting from electromagnetic radiation is getting worse and has become one of the four main pollution sources after air, water and noise. 3–6 Electromagnetic radiation poses great harm to the performance of electronic devices, information security, human health and the environment. Therefore, electromagnetic wave (EMW) absorbers have become one of the most studied materials in the last decade, 7 which can absorb electromagnetic energy and then convert electromagnetic energy into heat or other forms of energy so as to achieve the effect of reducing the reflection and propagation of incident waves.…”