MnO2 nanostructures deposited on graphene foams for broadband and lightweight electromagnetic absorption

Reduced Graphene Oxide Aerogels with Uniformly Self-Assembled Polyaniline Nanosheets for Electromagnetic Absorption

“…Raman scattering is used to determine the chemical structure of the samples. As is revealed in Figure a, two prominent Raman peaks of GO, GA, and GPA-3 are observed at 1341 and 1588 cm –1 , which are referred to as the D band and the G band, individually. , The G band characterizes the sp 2 hybridized carbon–carbon bonds arising from the graphitic layers, and the D band results from the defects and edge areas. , The decrease in the I D / I G value from 1.23 (GO) to 0.91 (GA) indicates that GO is effectively reduced and most defects and oxygen groups are removed in the assembly period. , Meanwhile, the intensity ratio of the D peak to G peak of GPA-3(0.96) is higher than that of GA (0.91), which resulted from the interfacial interaction between RGO and PANI in GPA-3. , These resultant defects can act as dipoles, which are favorable for polarization . For GPA-3, the peaks at 1161, 1214, and 1476 cm –1 are ascribed to the C–H stretching vibration of the quinoid/phenyl group, the C–N stretching vibration of the benzenoid ring, and the semiquinone radical cation structure, respectively.…”

“…In Figure a–e, GA and all GPAs exhibit an interconnected 3D network. The interconnected 3D porous structure enhances multiple reflection of EMW in the network as well as extends the propagation path of the incident wave, effectively enhancing EMW attenuation. , The surface of GA is smooth. The network of GPA-1 and GPA-2 is similar to that of GA, and no big PANI particles are found on RGO nanosheets, indicating the homogeneous distribution of PANI (Figure S1) on the RGO nanosheets.…”

“…In addition, unique 3D porous architecture not only decreases the weight of the absorber but also promotes multiple reflections and interface scattering of the incident EMW . To date, the researchers have gotten great advances in 3D graphene microwave absorption nanocomposites, such as 3D graphene/SiO 2 , 3D graphene/ZnO, and 3D graphene/MnO 2 …”

Effect of Surface Structure and Composition on the Electromagnetic Properties of Ti3C2Tx MXenes for Highly Efficient Electromagnetic Wave Absorption

“…In Figure b, there are two evident peaks at about 1342 and 1585 cm –1 , which can be assigned to the D band and G band, respectively . The intensity ratio I D / I G was evaluated for the amounts of defects in the graphitic carbon materials. − With an increase in the HF etching time, I D / I G increases from 0.98 to 1.05 because of the significant increase of defects and functional groups in the Ti 3 C 2 T x MXenes. Moreover, these defects and functional groups can generate polarization relaxation and electronic dipole polarization, which is conducive to microwave absorption. , It is worth noting that the strength of the D and G bands of titanium carbide was significantly enhanced after annealing, as shown in Figure S1.…”

Realizing Maximum Microwave Absorption of Poly(3,4-ethylenedioxythiophene) with a Data-Driven Method

“…For microwave-absorbing materials (MAMs), reflection loss (RL) and the effective bandwidth (Δ f 10 : the width of the peak where RL ≤ −10 dB, and ≥90% incident irradiation is lost) are two of the most important parameters for determining the quality of a material system for use in application. − Large RL and Δ f 10 values are highly desired for effective electromagnetic interference shielding. − Conducting polymers have been demonstrated as a highly utilized material class for coatings in applications including stealth technology and electromagnetic interference shielding. − They have been integrated into composite materials with great success, particularly in single plane-wave absorbers coated on metallic surfaces. − Materials such as polyaniline, polypyrrole, and poly­(3,4-ethylenedioxythiophene) (PEDOT) have been demonstrated as pure microwave-absorbing materials ,− and also been utilized in composites. − For example, microwave absorption with Δ f 10 4.5 GHz was demonstrated with PEDOT in an early study, and “broad” effective bandwidths were indicated with polypyrrole and polyaniline, while not accompanied many details . Liu et al utilized PEDOT as a substructure in a ternary composite containing graphene and cobalt ferrite to generate a strong microwave-absorption with an RL of −43.2 dB at 9.2 GHz and ascribed in part the activity of the ternary material to the high electrical conductivity of the added polymer .…”