Ultrathin graphene: electrical properties and highly efficient electromagnetic interference shielding

Abstract

Ultrathin graphene, a wonder material, exhibits great promise in various fields with its unique electronic structure and excellent physical, chemical, electrochemical, thermal and mechanical properties. Graphene presents great progress in electromagnetic interference (EMI) shielding.Herein, we review the advance in graphene-based EMI shielding materials. Towards graphene composites, we intensively evaluate EMI shielding efficiency and meaningfully describe the mechanism, such as polarization, hopping conduction and interface scattering. Moreover, we highlight an important direction for enhancing EMI shielding, the architectures, including alignment, paper, film and foam. Following that, the problems are summarized and the prospect is also highlighted for significant applications of ultrathin graphene in the field of EMI shielding.

Interfacially Engineered Sandwich‐Like rGO/Carbon Microspheres/rGO Composite as an Efficient and Durable Microwave Absorber

“…According to the free electron theory, [ 46 ] ε″ ≈ 1/2π ρfε 0 , where ρ , f , and ε 0 are the resistivity, the frequency, and the dielectric constant of free space, respectively, and thus it can be expected that high conductivity (i.e., low resistivity) of rGO will be in favor of enhancing the imaginary parts of complex permittivity. Although there is no clear quantitative relationship between conductivity and real parts of complex permittivity, a number of studies have provided an interesting clue that real parts will keep their steps with conductivity, [ 18,47 ] and this correlation may be possibly associated with the change in relaxation time according to the Debye theory. [ 48 ] Furthermore, it is widely accepted that various polarization processes from charged species are also responsible for the specifi c dielectric performance.…”

“…[ 14,15 ] However, sole graphene material suffers from limited loss mechanism caused by interfacial impedance mismatching, [ 15,16 ] thus it is usually employed as EM interference shielding material rather than EM absorbing material. [17][18][19] Incorporation of other lossy materials, especially magnetic metal and metal oxides, has been widely studied as the imperative solution to improve the matching of characteristic impedance and enhance the microwave absorption performance. [20][21][22][23][24][25][26][27][28][29] For example, graphene-coated Fe nanocomposites and Ni/graphene composites showed enhanced microwave absorption due to the charge transfer at metal/graphene interface and the polarization of free carriers; [ 20,21 ] Fe 3 O 4 /graphene, rGO-Fe 2 O 3 , and rGO/CNT-Fe 3 O 4 materials demonstrated optimum characteristic impedance and compatible dielectric and magnetic loss, which resulted in their strong refl ection loss in the frequency range of 12.0-16.0 GHz; [21][22][23] Graphene decorated with coreshell Fe@Fe 3 O 4 @ZnO nanoparticles was also fabricated, and Graphene-based composites offer immense potential for overcoming the challenges related to the performance, functionality, and durability in microwave absorption.…”

Recent Developments Concerning the Dispersion Methods and Mechanisms of Graphene

“…This monatomic layer structure makes graphene the thinnest and strongest material in the world [2]. Graphene also has excellent physical and chemical properties, such as mechanical properties [3], thermal properties [4], electrical properties [5], and optical properties [6]. Therefore, graphene has a wider value and prospects for practical application compared with other members of the carbon nanomaterials family, namely zero-dimensional fullerenes and one-dimensional carbon nanotubes.…”

Synthesis and Excellent Microwave Absorption Properties of ZnO/Fe3O4/MWCNTs Composites

“…The composites possess a high relative value of complex permittivity; thus, most incident microwaves are re°ected on the surface because of high surface resistance. Carbon materials exhibit strong microwave attenuation, 28,29 and semiconductors have been widely considered as microwave absorbers because of their strong dielectric loss. They possess a low relative real part value of complex permittivity and, therefore, can be used to adjust the complex permittivity of composites.…”