Direct Growth of Edge‐Rich Graphene with Tunable Dielectric Properties in Porous Si₃N₄ Ceramic for Broadband High‐Performance Microwave Absorption

Abstract

High‐performance graphene microwave absorption materials are highly desirable in daily life and some extreme situations. A simple technique for the direct growth of graphene as absorption fillers in wave‐transmitting matrices is of paramount importance to bring it to real‐world application. Herein, a simple chemical vapor deposition (CVD) route for the direct growth of edge‐rich graphene (ERG) with tailored structures and tunable dielectric properties in porous Si3N4 ceramics using only methyl alcohol (CH3OH) as precursor is reported. The large O/C atomic ratio of CH3OH helps to build a mild oxidizing atmosphere and leads to a unique structure featuring open graphite nanosteps and freestanding nanoplanes, endowing the ERG/Si3N4 hybrid with an appropriate balance between good impedance matching and strong loss capacity. Accordingly, the prepared materials exhibit superior electromagnetic wave absorption, far surpassing that of traditional CVD graphene and reduced graphene oxide‐based materials, achieving an effective absorption bandwidth of 4.2 GHz covering the entire X band, with a thickness of 3.75 mm and a negligibly low loading content of absorbents. The results provide new insights for developing novel microwave absorption materials with strong reflection loss and wide absorption frequency range.

Oriented Polarization Tuning Broadband Absorption from Flexible Hierarchical ZnO Arrays Vertically Supported on Carbon Cloth

“…Definitely, the electromagnetic absorption performance of a material depends on its electromagnetic parameters of complex permittivity and complex permeability. The real parts of complex permittivity (εʹ) and complex permeability ( µ ʹ) usually indicate the storage capability of electric and magnetic energy, while the imaginary parts (εʺ, µ ʺ) represent the loss capability of the incident electric and magnetic energy . According to the line transfer theory, electromagnetic (EM) parameters of CC@ZnO composites were gained via a vector network analyzer.…”

Graphene‐Based Materials toward Microwave and Terahertz Absorbing Stealth Technologies

“…Recently, Li and co‐workers reported the substantially improved absorption performance of an edge‐rich graphene (ERG)‐based microwave absorber prepared by CVD with methanol as the only gaseous source ( Figure a) . The ERG was directly grown in a wave‐transmitting porous Si 3 N 4 ceramic and thus formed a unique 3D graphene network with a remarkably increased number of intrinsic defects.…”

“…b) Schematic for the EM wave absorption mechanisms of ERG/Si 3 N 4 hybrids. Reproduced with permission . Copyright 2018, Wiley‐VCH.…”

Dielectric loss behavior and microwaves absorption properties of TiB2 ceramic

“…During the past decade, much effort has focused on the development of high-performance materials for microwaves absorption (MA) [1][2][3]. Conventionally developed MA materials are usually metal/metal oxides including ZnO nanorods [4], Ag nanofibers [5,6], NiCu alloy [7], and complex nanostructures; [8][9][10][11][12] conducting polymers including polyaniline(PANI) [13], poly (3, 4-ethylenedioxythiophene)(PEDOT) [14], and polypyrrole (PPy); [15][16][17][18] carbonaceous materials including reduced graphene oxide (RGO) [19,20], and carbon-nanotube (CNT); [21] and their hybrids including metal oxide/sulfide complexes [22,23], polymer complexes [24][25][26][27], RGO complexes [28][29][30], and CNT complex [31][32][33]. However, most of these reported MA materials cannot be considered to be used under harsh conditions, such as high temperature, high corrosion, high stress, and etc Therefore, searching for a MA material with excellent tolerance under harsh condition is highly desirable, but still a challenge up to date.…”