Synthesis of Fe 3 O 4 /polypyrrole/polyaniline nanocomposites by in-situ method and their electromagnetic absorbing properties

Facile Synthesis of Polyindole/Ni1-x Zn x Fe2O4 (x = 0, 0.5, 1) Nanocomposites and Their Enhanced Microwave Absorption and Shielding Properties

The present work reports the fabrication of polyindole (PIN)/Ni1-x Zn x Fe2O4 (x = 0, 0.5, 1) nanocomposites as efficient electromagnetic wave absorbers by a facile in situ emulsion polymerization method for the first time. The samples were characterized through Fourier transform infrared spectroscopy, UV-vis spectroscopy, X-ray diffraction, thermogravimetric analysis, scanning electron microscopy, high-resolution transmission electron microscopy, and vibrating sample magnetometry. The resulting polyindole/Ni1-x Zn x Fe2O4 (x = 0, 0.5, 1) nanocomposites offer better synergism among the Ni1-x Zn x Fe2O4 nanoparticles and PIN matrix, which significantly improved impedance matching. The best impedance matching of Ni1-x Zn x Fe2O4/polyindole (x = 0, 0.5, 1) nanocomposites was sought out, and the minimum reflection loss of the composites can reach up to -33 dB. The magnetic behavior, complex permittivity, permeability, and microwave absorption properties of polyindole/Ni1-x Zn x Fe2O4 (x = 0, 0.5, 1) nanocomposites have also been studied. The microwave absorbing characteristics of these composites were investigated in the 8-12 GHz range (X band) and explained based on eddy current, natural and exchange resonance, and dielectric relaxation processes. These results provided a new idea to upgrade the performance of conventional microwave-absorbing materials based on polyindole in the future.

Facile Synthesis of Sandwich-Like rGO/CuS/Polypyrrole Nanoarchitectures for Efficient Electromagnetic Absorption

Currently, electromagnetic pollution management has gained much attention due to the various harmful effects on wildlife and human beings. Electromagnetic absorbers can convert energy from electromagnetic waves into thermal energy. Previous reports have demonstrated that reduced graphene oxide (rGO) makes progress in the electromagnetic absorption (EA) field. But the high value of permittivity of rGO always mismatches the impedance which results in more electromagnetic wave reflection on the surface. In this work, sandwich-like rGO/CuS/polypyrrole (PPy) nanoarchitectures have been synthesized by a facile two-step method. The experimental result has shown that a paraffin composite containing 10 wt.% of rGO/CuS/PPy could achieve an enhanced EA performance both in bandwidth and intensity. The minimum reflection loss (RL) value of −49.11 dB can be reached. Furthermore, the effective bandwidth can cover 4.88 GHz. The result shows that the as-prepared rGO/CuS/PPy nanoarchitectures will be a promising EA material.

An optical-magnetic Material as a toxic gas filter and sensing device

The objective of this work is the development of a toxic gas detector/filter based on the production of porous polyaniline composites filled with magnetic nanoparticles. The composite produced was subjected to hydrogen sulfide gas as a preliminary test of its detection and sorption capacity, which were proven by gravimetric analysis. Analysis by light scattering and TEM indicated that magnetic nanoparticles with a size of approximately 5 nm were obtained through the proposed methodology. FTIR spectroscopy, UV-vis spectroscopy, TGA, and DSC were performed to prove the successful synthesis of the composite. To identify the specific properties of each constituent of the composite, the conductivity and magnetic force of the material were determined. The SEM results showed that the morphology was useful for the sorption process with the formation of pores in the polymer matrix, allowing the percolation of the gas for splicing by the nanoparticles. TGA, electrical conductivity, magnetic force, UV-vis spectroscopy, and EDS analyses were also performed after the detection/sorption tests to demonstrate the functioning of the material.

The objective of this work is the development of a toxic gas detector/filter based on the production of porous polyaniline composites filled with magnetic nanoparticles.

Review of electromagnetic interference shielding materials fabricated by iron ingredients

Iron (Fe) and its counterparts, such as Fe2O3, Fe3O4, carbonyl iron and FeO, have attracted the attention of researchers during the past few years due to their bio-compatibility, bio-degradability and diverse applications in the field of medicines, electronics and energy; including water treatment, catalysis and electromagnetic wave interference shielding etc. In this review paper, we aimed to explore iron based materials for the prevention of electromagnetic interference (EMI) by means of both reflection and absorption processes, including the standard methods of synthesis of Fe-based materials along with the determination of EMI performance. It is customary that a proper combination of two dielectric-losses, i.e. electrical and magnetic losses, give excellent microwave absorption properties. Therefore, we focused on the different strategies of preparation of these iron based composites with dielectric carbon materials, polymers etc. Additionally, we explained their positive and negative aspects.

NiS₂@MoS₂ Nanospheres Anchored on Reduced Graphene Oxide: A Novel Ternary Heterostructure with Enhanced Electromagnetic Absorption Property

For the purposes of strength, military equipment camouflage, and protecting the health of organisms, electromagnetic wave absorbing materials have received a lot of attention and are widely studied. In addition to having a strong absorption intensity and a wide effective absorption bandwidth, materials that are lightweight, thermally stable, and antioxidative are also highly desirable. In this study, we fabricated core⁻shell structured NiS₂@MoS₂ nanospheres anchored on reduced graphene oxide (rGO) nanosheets (NiS₂@MoS₂/rGO) by a simple two-step hydrothermal method. The combination ratio was adjusted to achieve proper impedance matching. The electromagnetic parameters and the absorption performance were investigated in detail. A composite loaded with 30 wt.% of the sample achieved a minimum reflection loss (RL) value of -29.75 dB and the effective bandwidth (RL value of less than -10 dB) ranged from 4.95 GHz to 18.00 GHz (13.05 GHz), with a thickness ranging from 1.5 mm to 4.0 mm. This study proved that the generated significant interfacial polarization and synergetic interaction between components can result in NiS₂@MoS₂/rGO composites with enhanced electromagnetic absorption performance.

Decorating MOF-Derived Nanoporous Co/C in Chain-Like Polypyrrole (PPy) Aerogel: A Lightweight Material with Excellent Electromagnetic Absorption

To clear away the harmful effects of the increment of electromagnetic pollution, high performance absorbers with appropriate impedance matching and strong attenuation capacity are strongly desired. In this study, a chain-like PPy aerogel decorated with MOF-derived nanoporous Co/C (Co/C@PPy) has been successfully prepared by a self-assembled polymerization method. With a filler loading ratio of 10 wt %, the composite of Co/C@PPy could achieve a promising electromagnetic absorption performance both in intensity and bandwidth. An optimal reflection loss value of −44.76 dB is achieved, and the effective bandwidth (reflection loss lower than −10 dB) is as large as 6.56 GHz. Furthermore, a composite only loaded with 5 wt % Co/C@PPy also achieves an effective bandwidth of 5.20 GHz, which is even better than numerous reported electromagnetic absorption (EA) materials. The result reveals that the as-fabricated Co/C@PPy—with high absorption intensity, broad bandwidth, and light weight properties—can be utilized as a competitive absorber.

Controllable Fabrication of Fe₃O₄/ZnO Core⁻Shell Nanocomposites and Their Electromagnetic Wave Absorption Performance in the 2⁻18 GHz Frequency Range

In this study, Fe₃O₄/ZnO core⁻shell nanocomposites were synthesized through a chemical method of coating the magnetic core (Fe₃O₄) with ZnO by co-precipitation of Fe₃O₄ with zinc acetate in a basic medium of ammonium hydroxide. The phase structure, morphology and electromagnetic parameters of the Fe₃O₄/ZnO core⁻shell nanocomposites were investigated. The results indicated that the concentration of the solvent was responsible for controlling the morphology of the composites, which further influenced their impedance matching and microwave absorption properties. Moreover, Fe₃O₄/ZnO nanocomposites exhibited an enhanced absorption capacity in comparison with the naked Fe₃O₄ nanospheres. Specifically, the minimum reflection loss value reached −50.79 dB at 4.38 GHz when the thickness was 4.5 mm. It is expected that the Fe₃O₄/ZnO core⁻shell structured nanocomposites could be a promising candidate as high-performance microwave absorbers.

Hollow cube-like CuS derived from Cu2O crystals for the highly efficient elimination of electromagnetic pollution

In this study, hollow cube-like CuS was fabricated via a one-step reaction to investigate high electromagnetic wave absorption performance.