The porous Fe 3 O 4 /carbon core/shell nanorods were fabricated via a three-step process. R-Fe 2 O 3 nanorods were first obtained, and R-Fe 2 O 3 /carbon core/shell nanorods were subsequently fabricated using glucose as a carbon source by a hydrothermal method, in which the thickness of the carbon coating was about 3.5 nm. Fe 3 O 4 /carbon core/shell nanorods were synthesized after an annealing treatment of the product above under a mixture of Ar/H 2 flow. After the H 2 deoxidation process, the Fe 3 O 4 core exhibited a character of porosity; the thickness of the carbon shell was decreased to about 2.5 nm, and its degree of graphitization was enhanced. The interesting core/ shell nanostructures are ferromagnetic at room temperature, and the Verwey temperature was about 120 K. Electromagnetic properties of the core/shell nanorodÀwax composite were investigated in detail. The maximum reflection loss was about À27.9 dB at 14.96 GHz for the composite with a thickness of 2.0 mm, and the absorption bandwidth with the reflection loss below À18 dB was up to 10.5 GHz for the absorber with the thickness of 2À5 mm. The excellent electromagnetic wave absorption properties of the porous Fe 3 O 4 /carbon core/shell nanorods were attributed to effective complementarities between the dielectric loss and the magnetic loss.

This paper presents for the first time a successful synthesis of quaternary nanocomposites consisting of graphene, Fe(3)O(4)@Fe core/shell nanopariticles, and ZnO nanoparticles. Transmission electron microscopy measurements show that the diameter of the Fe(3)O(4)@Fe core/shell nanoparitcles is about 18 nm, the Fe(3)O(4) shell's thickness is about 5 nm, and the diameter of ZnO nanoparticles is in range of 2-10 nm. The measured electromagnetic parameters show that the absorption bandwidth with reflection loss less than -20 dB is up to 7.3 GHz, and in the band range more than 99% of electromagnetic wave energy is attenuated. Moreover, the addition amount of the nanocomposites in the matrix is only 20 wt %. Therefore, the excellent electromagnetic absorption properties with lightweight and wide absorption frequency band are realized by the nanocomposites.

We developed a new strategy, i.e., a seed-assisted method, to fabricate a three-dimensional (3D) SiO2@Fe3O4 core/shell nanorod array/graphene architecture. The fabrication processes involved deposition of β-FeOOH seeds on the graphene surfaces in the ferric nitrate aqueous solution, subsequent growth of β-FeOOH nanorod arrays on the graphene surfaces in the ferric chloride aqueous solution under hydrothermal conditions, deposition of SiO2 coating on the surfaces of β-FeOOH nanorods, and final formation of the 3D architecture by a thermal treatment process. Scanning electron microscopy and transmission electron microscopy measurements showed that the SiO2@Fe3O4 core/shell nanorods with a length and diameter of about 60 and 25 nm, respectively, were almost grown perpendicularly on both side surfaces of graphene sheets. The measured electromagnetic parameters showed that the 3D architecture exhibited excellent electromagnetic wave absorption properties, i.e., more than 99% of electromagnetic wave energy could be attenuated by the 3D architecture with an addition amount of only 20 wt% in the paraffin matrix. In addition, the growth mechanism of the 3D architecture was proposed, and thus, the strategy presented here could be used as a typical method to synthesize other 3D magnetic graphene nanostructures for extending their application areas.

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.

3D hierarchical MoS2 nanoflake array/carbon cloth is synthesized with a thickness of MoS2 nanoflakes <15 nm. A full Li battery based on the cloth exhibits good electrochemical performance and high flexibility.