Bo Wen

Reduced graphene oxides: light-weight and high-efficiency electromagnetic interference shielding at elevated temperatures.

Chemical graphitized r-GOs, as the thinnest and lightest material in the carbon family, exhibit high-efficiency electromagnetic interference (EMI) shielding at elevated temperature, attributed to the cooperation of dipole polarization and hopping conductivity. The r-GO composites show different temperature-dependent imaginary permittivities and EMI shielding performances with changing mass ratio.

Graphene/polyaniline nanorod arrays: synthesis and excellent electromagnetic absorption properties

In the paper, we find that graphene has a strong dielectric loss, but exhibits very weak attenuation properties to electromagnetic waves due to its high conductivity. As polyaniline nanorods are perpendicularly grown on the surface of graphene by an in situ polymerization process, the electromagnetic absorption properties of the nanocomposite are significantly enhanced. The maximum reflection loss reaches −45.1 dB with a thickness of the absorber of only 2.5 mm. Theoretical simulation in terms of the Cole–Cole dispersion law shows that the Debye relaxation processes in graphene/polyaniline nanorod arrays are improved compared to polyaniline nanorods. The enhanced electromagnetic absorption properties are attributed to the unique structural characteristics and the charge transfer between graphene and polyaniline nanorods. Our results demonstrate that the deposition of other dielectric nanostructures on the surface of graphene sheets is an efficient way to fabricate lightweight materials for strong electromagnetic wave absorbents.

Graphene–Fe3O4 nanohybrids: Synthesis and excellent electromagnetic absorption properties

Graphene (G)–Fe3O4 nanohybrids were fabricated by first depositing β-FeOOH crystals with diameter of 3–5 nm on the surface of the graphene sheets. After annealing under Ar flow, β-FeOOH nanocrystals were reduced to Fe3O4 nanoparticles by the graphene sheets, and thus G–Fe3O4 nanohybrids were obtained. The Fe3O4 nanoparticles with a diameter of about 25 nm were uniformly dispersed over the surface of the graphene sheets. Moreover, compared with other magnetic materials and the graphene, the nanohybrids exhibited significantly increased electromagnetic absorption properties owing to high surface areas, interfacial polarizations, and good separation of magnetic nanoparticles. The maximum reflection loss was up to −40.36 dB for G–Fe3O4 nanohybrids with a thickness of 5.0 mm. The nanohybrids are very promising for lightweight and strong electromagnetic attenuation materials.

Enhanced wave absorption of nanocomposites based on the synthesized complex symmetrical CuS nanostructure and poly(vinylidene fluoride)

Complex symmetrical CuS nanostructures were synthesized in large scale by a simple wet chemical method at low temperature. As a semiconductor material with superstructure, CuS was well characterized and firstly introduced into PVDF to form nanocomposites. The substantial enhancement of wave absorption (−102 dB at 7.7 GHz) was observed by addition of CuS with a low filler loading (5 wt%). The mechanism for the enhanced wave absorbing properties was explained in detail.

Synthesis and growth mechanism of 3D α-MnO2 clusters and their application in polymer composites with enhanced microwave absorption properties

α-MnO2 hollow-sphere-like clusters composed of nanotubes have been synthesized on a large scale by a simple hydrothermal method. The results show that the 3D hollow-sphere-like clusters are assembled by 1D nanotubes (HSC-nanotubes) with diameter of around 80–100 nm and length of around 2–3 μm. The influences of reaction time and temperature on the morphology of the final products are investigated, while the formation mechanism is also discussed. The α-MnO2 hollow-sphere-like clusters possess much better dielectric properties than the bulk material, which is directly related to their special nanostructures. Besides, the synthesized α-MnO2 hollow-sphere-like clusters were used as fillers in the fabrication of α-MnO2/PVDF nanocomposites, which have excellent wave-absorption properties with low filler loading. The enhanced properties are caused by a synergic effect between α-MnO2 and PVDF, as explained in this research.