Synthesis and electromagnetic wave absorption performance of NiCo₂O₄ nanomaterials with different nanostructures

Abstract

Bayberry-like, needle array-like and urchin-like NiCo2O4 hierarchical structures were synthesized by simple hydrothermal reactions.

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

“…With the increase of frequency, ε′ of all samples displays an obvious downward trend in Figure 5a, indicating the typical frequency dispersion behavior. 42,43 The ε′ values of Ti 3 C 2 T x specimens are significantly increased in contrast with the ones of pristine Ti 3 AlC 2 powder, as shown in Figure 5a. As etching time increases from 12 to 36 h, the ε′ and ε″ values of assynthesized Ti 3 C 2 T x gradually increase, implying the remarkable increase of contribution to electromagnetic wave attenuation.…”

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.…”

“…According to the SEM of the samples, the formation mechanism of uniformly distributed PANI nanosheets is proposed. In PANI/GO dispersion, the PANI has poor solubility in water, and thus, the PANI nanosheets tend to attach onto GO sheets forced by the π–π interaction, hydrogen bonding, and electrostatic interaction between GO and PANI. , These interactions facilitate the uniform distribution of PANI . When the content of PANI is adjusted, the amount of PANI attached to the GO nanosheets is precisely controlled and the microstructure of GPAs can be further adjusted.…”

“…Currently, with the ever-accelerating improvement of information technology and the popularity of electronic equipment, electromagnetic wave (EMW) pollution is seriously threatening the human health and ecological environment. − Therefore, the EMW absorbing materials have become a research hotspot, which can convert electromagnetic energy into thermal energy or dissipate the EMW by interference. , The conventional EMW absorbing materials, such as ceramics, ferrite, and metal powders, have shown good EMW absorption performance in some cases. However, these materials cannot satisfy the practical demands because of their large density and narrow bandwidth.…”

Fabrication of N-Doped Reduced Graphite Oxide/MnCo2O4 Nanocomposites for Enhanced Microwave Absorption Performance

“…These nonferrites find application in a variety of fields, such as lithium-ion batteries, supercapacitors, fuel cell, sensors, electrocatalysts, and magnetic materials, etc. In addition, investigations have also been made to study the attenuation of EM wave by MnCo 2 O 4 microparticles, mesoporous NiCo 2 O 4 , flower-like NiCo 2 O 4 , NiCo 2 O 4 nanoflake, hierarchical NiCo 2 O 4 , hierarchical NiCo 2 O 4 , , 1D NiCo 2 O 4 , Hollow NiCo 2 O 4 , ZnCo 2 O 4 hierarchical nanostructures, etc. Moreover, different nanostructures of NiCo 2 O 4 have been prepared in aqueous solution via a facile template-free hydrothermal synthesis method using different metal nitrate/urea ratio .…”