A composite with a gradient distribution of graphene and its anisotropic electromagnetic reflection

Abstract

An electrochemical method was introduced to prepare graphene/polyurethane foams with gradient graphene distribution, and this composite shows obvious anisotropic reflection of electromagnetic waves.

Analytical Modeling of Wave Absorption Performance in Gradient Graphene/Polymer Nanocomposites

“…Graded distributed graphene is advantageous for enhancing the wave-absorption performance of composites. For example, as reported by Zhang et al [ 21 ], reduced graphene oxide (RGO)/polyurethane composites with a gradient distribution of RGO exhibited satisfactory wave-absorption performance. When the electromagnetic wave was incident from the surface with low graphene concentration, the reflection loss of the composites was −30 dB across the entire X-band, and over 99.5% of the wave was absorbed.…”

MXene Nanosheet/Polypyrrole Composite Felt with a Continuous Impedance-Gradient Structure for Electromagnetic Wave Absorption

“…In this way, the absorption frequency band and the absorption level can be increased. 11,12 In our previous work, the integrated-impedance-gradient absorbing structure was proposed for the first time. This structure was realized by the gasphase polymerization method, but the gas diffusion was difficult to control.…”

“…This requires the content of the absorbing agent to increase from one end to the other (instead of uniform distribution) to reduce the impedance mismatch between the air and the material surface. In this way, the absorption frequency band and the absorption level can be increased. , In our previous work, the integrated-impedance-gradient absorbing structure was proposed for the first time. This structure was realized by the gas-phase polymerization method, but the gas diffusion was difficult to control …”

Electromagnetic Absorption by Magnetic Oxide Nanomaterials: A Review

“…Absorptive electromagnetic absorption materials can be classified into two categories based on the type of loss mechanism: One category is dielectric loss materials such as metal oxides, 14−16 metal sulfides, 17,18 carbides, 19,20 and carbon materials. 21,22 Such as semiconductors, with a low dielectric constant, good impedance matching properties, and chemical stability, yet a single material cannot achieve high loss of electromagnetic waves.…”

“…Absorptive electromagnetic absorption materials can be classified into two categories based on the type of loss mechanism: One category is dielectric loss materials such as metal oxides, − metal sulfides, , carbides, , and carbon materials. , Such as semiconductors, with a low dielectric constant, good impedance matching properties, and chemical stability, yet a single material cannot achieve high loss of electromagnetic waves. The carbon material itself has the advantages of low density and high conductive loss, but its poor impedance matching properties make it difficult for electromagnetic waves to enter the inner part of the material. , Another category is magnetic loss material.…”